Question 1155634

when maria was 6 years old. Andrew was twice her age, maria is 9 years old now. How old is Andrew.
<pre>Maria is now 9, so 3 years ago, she was 6
Since at that time, Andrew was twice her age, then at that time (3 years ago), Andrew was 2(6), or 12 years-old. 
Three years after (now), obviously, {{{highlight_green(matrix(1,6, Andrew, is, 12 + 3, "=", 15, years-old))}}}.