Answer:
7 miles
Step-by-step explanation:
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.
Avg speed of the round trip= 2*28*4/(28+4)= 7 mi/hr
RT=7*2=14 miles
--> 7 miles each way.
