Question

9.
A boy rides away from home in an automobile at the rate of 28 miles an hour and
walks back at the rate of 4 miles an hour. The round trip requires 2 hours. How far
does he ride?​

Answer 1

Let x be the number of hours he rides away from home at 28 mph.

Then, since the speed of the automobile is 7 times his walking speed, the number of hours he spends walking is 7x.

Then the total time, which is 2 hours, is equal to x plus 7x, or 8x.

8x = 2 --> x = 1/4

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.

Answer: 7 miles