Question 1154094
Mary is less than 15 years old.  She is half as old as Justin.  In 11 years she will be 2/3 years old as Justin.  How old is Justin?
<pre>Mentioning that Mary is < 15 years-old serves no purpose, whatsoever.
Let Justin's age be J
Then Mary's is: {{{J/2}}}
We then get: {{{matrix(1,3, J/2 + 11, "=", (2/3) * (J + 11))}}}
3J + 66 = 4J + 44 ------ Multiplying by LCD, 6
3J - 4J = 44 - 66
- J = - 22
J, or {{{highlight_green(matrix(1,6, Justin, "is:", (- 22)/(- 1), "=", 22, years-old))}}}