Two or more linear equations that are grouped together are called a system. That means that a system of linear equations is when two or more linear equations are being solved at the same time. For example:  8x - 3y = -3 5x - 2y = -1 These are two linear equations that you must solve at the same time, meaning you must use both equations to solve both equations. The answer to the linear equations problem is an ordered pair of numbers that make both of the equations true. In the case of our example, you are trying to find out what numbers ‘x’ and ‘y’ represent that will make both of the equations true. In the case of this example, x = -3 and y = -7. Plug them in. 8(-3) - 3(-7) = -3. This is TRUE. 5(-3) -2(-7) = -1. This is also TRUE. The numerical coefficient is simply the number that comes before a variable. You will use these numerical coefficients when using the elimination method. In our example equations, the numerical coefficients are: 8 and 3 for the first equation; 5 and 2 for the second equation. When you use elimination to solve a multivariable linear equation, you get rid of one of the variables you are working with (such as ‘x’) so that you can solve the other variable (‘y’). Once you find ‘y’, you can plug it into the equation and solve for ‘x’ (don’t worry, this will be covered in detail in Method 2). Substitution, on the other hand, is where you begin working with only one equation so that you can again solve for one variable. Once you solve one equation, you can plug in your findings to the other equation, effectively making one large equation out of your two smaller ones. Again, don’t worry—this will be covered in detail in Method 3. Solving for three variables can actually be done in the same way that equations with two variables are solved. You can use elimination and substitution, they will just take a little longer than solving for two, but are the same process.
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One-sentence summary -- Understand what multi-variable equations are. Know that you are trying to figure out the values of the variables, or unknowns. Know what a numerical coefficient is. Understand the difference between solving with elimination and solving with substitution. Understand that there can be linear equations that have three or more variables.


Imagine you are holding a pair of binoculars up to your eyes. Your thumbs should be below your eyes, while your index fingers are just above your eyebrows. Apply firm pressure against your forehead with your index fingers. You will have to work against your fingers to accomplish this task. Apply downward pressure for two seconds. Relax the position of your hands and your eyebrows. Repeat this exercise 3 more times. On your last repetition, hold the position for ten seconds, which will strengthen and tighten the forehead muscles. Perform this exercise daily along with the other facial yoga poses discussed in the article so that your forehead is smooth and line-free.
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One-sentence summary -- Make a C shape with each hand. Use your index fingers to pull the skin on your forehead down. Try to raise your eyebrows upwards and open your eyes wide. Hold this position for two seconds. Relax and repeat. Hold for ten seconds on the last repetition. Repeat daily.


To determine where you need to cut your mat, you first need to know how big the picture is. Take your ruler and measure both the width and the height of the photo; write down your measurements on a piece of paper. If you’re framing a photo with a white border, measure from where the actual photo starts so that the white won’t be visible once it’s framed. Now that you know how big the picture is and how big the frame is, you can do some math to determine where you’ll need to cut the mat board. In general, you want anywhere from a 1⁄2 inch (1.3 cm) border to a 2 inches (5.1 cm) border going all the way around the photo. For example:  If your picture is 7 inches (18 cm) wide and 12 inches (30 cm) tall and the frame is 16 inches (41 cm) wide and 20 inches (51 cm) tall, you’ll subtract the picture’s height from the frame’s height and divide that answer by 2 to figure out where you’ll need to make your mat cuts. Similarly, you’ll subtract the picture’s width from the frame’s width and divide that answer by 2 to determine where you need to cut for the width of the mat. If your picture is a lot smaller than the frame, you’ll be left with a much bigger mat border. Always mark the back of the board rather than the front. If you mark on the front, you’ll have to erase your pencil lines which could change the color of the mat or ruin its appearance (especially if it’s not white). Use your metal ruler to mark off the entire square that needs to be removed to create the border for the picture. Use a pencil rather than a marker to make your notations. A marker could bleed into the mat board or could get on your hand and then transfer to the front of the board or picture later on. Line up your metal ruler along one of the lines for the border. Use your X-ACTO knife to carefully cut along the ruler, making sure to start and stop at the intersections with the other lines. If you go too far, you’ll be cutting into the border itself and will need to start over. Cut the board on all 4 sides and then pop out the interior section to reveal the border. You can save that interior section of mat board to use on other projects. You could always make another border for a smaller picture, or use it in other crafting projects.
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One-sentence summary --
Measure how big the picture is that you need to mat. Calculate how big the border should be. Mark the back of the mat board so you can line up your cuts. Cut out the center of the mat based on the measurements you made.