Question 1165625

The sum of the ages of mark and Sarah is 102 years. 11 years ago mark was 3 times Sarah’s age. How old is mark now? 
<pre>Let Mark's age be M
Then Sarah's is: 102 - M
We then get: M - 11 = 3(102 - M - 11)
M - 11 = 3(91 - M)
M - 11 = 273 - 3M
M + 3M = 273 + 11
4M = 284
Mark, or {{{highlight_green(matrix(1,6, M, "=", 284/4, "=", 71, years-old))}}}