Let the speed of the law which sates from place
A=xkm/h
the speed of the car which starts from place B=ykm/h
Case-I- when the car haves in same direction.
Distance = time x speed
=5xkm
The distance covered by the car which starts from place A=5x
The distance covered by the car which starts from place B=5y
AC−BC=AB
5X−5Y=100
x−y=20 .......(1)
Case - ii When the car moves in opposite direction
The distance covered by the car which starts from place A=1xkm
The distance covered by the car which
starts from place B=1ykm
AC+BC=AB
x+y=100 ........(2)
Adding equation (1) and (2)
2x=120
x=60
putting x=60 in equation (2)
60+y=100⇒y=40
The speed of the car which starts from place A=60km/h
The speed of the car which starts from place B=40km/h
So, product of their speed is 2400km/h