Question 511708
William = 12 years old
His brother = 12/4 = 3 years old
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In the future, William will be 12+x years old, and his brother will be 3+x years old,
where 'x' is a number of years.
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At what point will 12+x = 2(3+x)?
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12 +x = 2(3 +x) = 6 +2x
-x = -6
x = 6
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Answer:  In 6 years, William will be twice as old as his brother.
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Always check your answer.
12+6 = 18
3+6 = 9
18 = 2*9
Correct
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Done.