SOLUTION: A man travels 29 km on a good road at a certain average speed. On a bad road, he reduces his average speed by 42 km/h and he finds that it takes him the same time to cover 15 km on

Question 1058586: A man travels 29 km on a good road at a certain average speed. On a bad road, he reduces his average speed by 42 km/h and he finds that it takes him the same time to cover 15 km on the bad road. Find his average speed (a) on the good road (b) on the bad.
Answer by solve_for_x(190) (Show Source): You can put this solution on YOUR website!
Let x represent his speed on the "good road".

If he travels 29 km at this speed, the time taken is 29/x hours.

His speed on the "bad road" would be x - 42.

If he travels 15 km at this speed, the time taken is 15/(x - 42) hours.

Since it takes him the same time to cover both distances, you can write:

29/x = 15/(x - 42)

Multiplying both sides by x gives:

29 = 15x/(x - 42)

Then multiplying both sides by (x - 42) leaves:

29(x - 42) = 15x

29x - 1218 = 15x

29x - 15x = 1218

14x = 1218

x = 87 km/hr

Solution: His speed on the good road is 87 km/hr. His speed
on the bad road would be 87 - 42 = 45 km/hr.
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