Answer: speed of boat A is 12 km/h
Speed of boat B is 5 km/h
Explanation:
Let x represent the speed of boat B.
If boat B travels at a speed 7km/hr less than boat A, it means that the speed at which boat A travels is
(x + 7) km/h
After 4 hours, the two boats are 68 km apart.
Distance = speed × time
Distance covered by boat A in 4 hours is
4(x + 7)
Distance covered by boat B is
4 × x = 4x
The distance covered by both boats in 4 hours is 68 km. It means that
4x + 4(x + 7) = 68
4x + 4x + 28 = 68
8x + 28 = 68
8x = 68 - 28
8x = 40
x = 40/8
x = 5 km/h
The speed of boat A is
x + 7 = 5 + 7 = 12 km/h