Question

find the speed of both cars.

Answer 1

Distance = 70 km
Let the speed of one car be 'A' km/hr and other car b be 'B' km/hr
When they travel in same direction:
Relative speed = A - B km/hr
When they travel in opposite direction:
Relative speed = A + B km/hr
In the same direction, they meet after 7 hours.
70/(A-B) = 7
10/A-B = 1
A - B = 10....(i)
Travelling in opposite directions, they meet after 1 hour.
70/A+B = 1
A + B = 70....(ii)
(i) + (ii)---- 2 A = 80
A = 40 km/hr
A - B = 10
40 - B = 10
B = 30 km/hr
Hence Speed of one car = 40 km/hr
The speed of other car = 10 km/hr.
Hope it helps.