Question

The sum of twice a number and4 is 80, find the number

Answer 1

If X is the unknown number, then the sum of that number and 8 is represented as X + 8. And twice

the sum of the number and 8 is 2(x + 8). The problem tells you that this must equal 40.

In equation form this is:

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2(X + 8) = 40

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Multiply out the left side by multiplying 2 times each of the terms in parentheses to get:

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2X + 16 = 40

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Get rid of the 16 on the left side by subtracting 16 from both sides to get:

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2X = 24

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Solve for X by dividing both sides of this equation by 2 and you have that X, the unknown

number, is:

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X = 24/2 = 12

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Check: Does twice the sum of 12 and 8 = 40??? 12 + 8 equals 20 and twice 20 is, in fact,

40. So the answer checks. X = 12 is the answer.

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Hope this helps you to understand the problem