Let's first convert that amount of money into cents, which makes 336 cents. Then, let's denote the amount of money one of the boys has with x. The other boy has got 3x-12 amount of money. We can construct an equation. . Solving it we find that x=87 cents or $ 0.87 and the other boy holds $2.49 amount of money.
A.) -13 b.) 17 c.) 80 d.) 1 All your doing is substituting x for the number in the parenthesis and matching it with the correct function. For example, f(-3) would be 2(-3)-7 which is equal to -6-7 which is -13.