Cho is driving a car. He gets to his destination, which is 72 miles away, in 1 hour and 30 minutes.

Question

a. The equation d=rt can be used to model Cho's drive, where d us the distance traveled, r is the speed of the car and, and t is the amount of time spent traveling. Substitute Cho's time and distance into the equation.
72 = 90 (is this correct)
b. Solve the equation in part a to find Cho's speed. Show your work

Answer 1

A. Yeah, almost. :)
d = rt
Since d = 72 miles and t = 1.5 hours or 90 minutes,
72 = 1.5r (if you want r to have units in miles/hour)
72 = 90r (if you want r to have units in miles/minute)

B.
72 = 1.5r
r = 72/1.5
r = 48 miles/hour

72 = 90r
r = 72/90
r = 0.8 mile/min

Answer 2

what is r