Answer
$19 \ in.$
Work Step by Step
Let $C$ be the circumference of a circle:
$C=2 \pi r$ or, $C=\pi d~~~~(1)$
Here, $r$ represents radius and $d$ is diameter.
The circumference of a compact car is: $C=\pi d =25 \pi \ in.$
Now, the circumference of the pick-up truck is: $C=\pi d =31 \pi \ in.$
In order to get the distance travelled by a wheel, we will subtract the two circumferences.
That is, $d=31 \pi-25 \pi=6 \pi =(6)(3.14)=19 \ in.$
