A boy rides away from home in an automobile at the rate of 28 km/h and walks back at the rate of 4 km/h. The round trip is x km. Write and simplify an expression that will represent the total time, in hours, the boy travelled. (distance=speed *time)
Then, the total time, which is 2 hours, is equal to x plus 7x, or 8x. So the amount of time he spends in the automobile is x=1/4 hour. The distance he travels in 1/4 hour at 28 mph is 7 miles.
