distance equation

Question

A person drove at a speed of

56 miles per hour on a back road during a recent trip. They can drive the same distance at

105 mph on the interstate in four hour less. What is the distance they drove on the back​ road?

Answer 1

Use the equation of motion: distance = rate x time

Both cars travel equal distance, but at different rates of speed.

(d) road = 56 x t

(d) inter = 105 x (t-4) = 56 t

Solve for t:

56t = 105t - 420

49t = 420

t = 8.6 hrs

(d)road = 56 mph x 8.6 hrs = 480 miles.