Question 38
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The very first step is to choose a variable to solve for. Traditionally, I always solve for "y" first, and then I'll solve for "x". Here's the problem, step by step:
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x + y = 4x - y = 5 {<i>Here, I'll solve for "y"</i>}
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x + y = 5 {<i>Remember that the problem establishes that each part of the problem containing variables are equal to "5"</i>}
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y = 5 - x
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4x - y = 5 {<i>Again, each part containing variables is equal to "5"</i>}
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4x - (5 - x) = 5 {<i>We solved for "y" earlier, so now we plug it in to the equation to solve for "x"</i>}
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5x - 5 = 5
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5x = 10
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x = 2
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y = 5 - x {<i>Go back to how we solved for "y" and plug in the value for "x"</i>}
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y = 5 - 2
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y = 3
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Presto: x = 2, and y = 3. Problem solved! The important step is to isolate one of the variables first and solve for it. Then you can plug and chug your way to answer. Hope this helps.