17. During rush hour, Jerry's father needs 20 minutes to drive him to school. One day, they did not encounter rush hour traffic, and the car was 18 km/h faster, so it only took 12 minutes to get Jerry to school. The distance from home to school is ( ) km.
(A) 4
(B) 6
(C) 8
(D) 9
(E) 12
17. D.

Let the distance from home to school be $x$ kilometers, and the speed of the car during peak hours be $y$ kilometers/hour. Then
$$
\left\{\begin{array}{l}
\frac{x}{y}=\frac{20}{60}, \\
\frac{x}{y+18}=\frac{12}{60}
\end{array} \Rightarrow x=9\right.
$$