#### Answer

(a) $\int_{0}^{15}f(t) ~dt$
(b) $\int_{30}^{\infty}f(t) ~dt$

#### Work Step by Step

(a) We can write an integral for the probability that you drive to school in less than 15 minutes:
$\int_{0}^{15}f(t) ~dt$
(b) We can write an integral for the probability that it takes you more than half an hour to get to school:
$\int_{30}^{\infty}f(t) ~dt$