Problem 2-62 - Distance and speed

A truck travels at $80 \;km/h$ for $30\; min$, then at $60 \;km/h$ for $1.5 \;hr.$ Assuming 2 significant digits in the given numbers, calculate the truck's

(a) total distance traveled, and
(b) average speed.

Which statement is correct?

(A)   The truck travels at a constant speed for the whole trip.

(B)   The truck travels at two different speeds for the whole trip.

(C)   The truck's speed is constantly changing.