A2. Mother answered the question about how old her son is with a riddle: If we subtract three times as many years as he had six years ago from twice his current age, we get how old he is today. How old is the son today?
(A) 3 years
(B) 18 years
(C) 9 years
(D) 6 years
(E) 27 years
A2. Suppose today is $x$ years old and we write the equation $2 x-3(x-6)=x$. We remove the parentheses, organize the equation, and get the solution $x=9$.