f(t) = 2t + 8
If t stands for the number of minutes she has been selling tickets, then we know that we must have 2t in the equation since she sells 2 tickets per minute. And since the only two left are either f(t) = 2t - 8 or f(t) = 2t + 8, the answer must be
f(t) = 2t + 8 because she is 8 tickets, not -8.
