Question 770384
Noah is 40, Mary is 13. How many years ago was Noah four times as old as Mary?
<pre>
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:


              {{{(matrix(5,1,

"Noah's",age,x,years, ago))}}}{{{""=""}}}{{{4*(matrix(5,1,

"Mary's",age,x,years, ago))}}}

                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</pre>