Answer:
Distance between school and home = 105 miles.
Explanation:
Let distance = D miles
Time to take walking/jogging, t1 = D/6 hours
Time by car, t2 = D/35 hours
Average time, t
= (t1+t2)/2
= D(1/6+1/35)
= (D/210)(35+6)
=41D/210 hours
Given t = t1-3 hours
41D/210 - D/6 = 3
Solve for D
41D/210 - 35D/210 = 3
(41-35)D/210 = 3
6D/210 = 3
D = 3*210/6 = 105 miles.
(Appreciate very much Diana's efforts to walk/job 105 miles to school, and we understand how lucky we are in most of Europe and North America)