SOLUTION: Noah is 40, Mary is 13. How many years ago was Noah four times as old as Mary?

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Question 770384: Noah is 40, Mary is 13. How many years ago was Noah four times as old as Mary?
Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
Noah is 40, Mary is 13. How many years ago was Noah four times as old as Mary?
Let the answer be "x years ago".

Noah's age x years ago = 40-x

Mary's age x years ago = 13-x

The equation comes from:


              %28matrix%285%2C1%2C%0D%0A%0D%0A%22Noah%27s%22%2Cage%2Cx%2Cyears%2C+ago%29%29%22%22=%22%224%2A%28matrix%285%2C1%2C%0D%0A%0D%0A%22Mary%27s%22%2Cage%2Cx%2Cyears%2C+ago%29%29

                40-x = 4(13-x)
                40-x = 52-4x
                  3x = 12
                   x = 4

Answers: 4 years ago Noah was 36.  4 years age Mary was 9.

That checks because 36 is 4 times 9.

Edwin