Question 81746
Let "one number" be represented by x. Then "the other number" is 12 more than it. So that
number [which is the bigger number] is x + 12.
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So you have the two numbers of x and x + 12
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Next you are told that if you add the smaller number [x] to twice the larger number [2*(x+12)]
the answer is 39. In equation form this becomes:
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x + 2*(x + 12) = 39
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Do the distributed multiplication on the left side by multiplying 2 times each of the terms
in the parentheses. When you do, the equation becomes:
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x + 2x + 24 = 39
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Combine the two terms on the left side that each contain an "x". When you add them the
equation becomes:
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3x + 24 = 39
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Next get rid of the 24 on the left side by subtracting 24 from both sides of this equation.
Subtracting 24 from both sides results in:
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3x = 15
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Finally solve for x by dividing both sides of this equation by the multiplier of x (the
multiplier is 3, so divide both sides by 3) and you get:
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x = 5
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You were asked to find the bigger of the two numbers. You now know that the smaller
number (x) is 5 and the problem tells you that the bigger number is 12 more than that.
So the bigger number is 5 + 12 or 17.
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The two numbers are 5 and 17.
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Check ... does the smaller number plus twice the bigger number add up to be 39? Twice the
bigger number is 2 times 17 or 34 and then adding the smaller number to that you get:
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5 + 34 
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and that does, in fact, add up to 39 just as the problem required.  So the answer checks
out correctly.
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Hope this helps you to understand this problem a little better.