Places M and N are 90 km apart from each other on a national highway. A truck starts from M and another from N at the same time. If they go in the same direction, then they meet in 9 hours and if they go in opposite directions they meet in 9/7 hours. The speed of the trucks are _______.
A 90 km/hr, 40 km/hr
B 40 km/hr, 30 km/hr
C 20 km/hr, 60 km/hr
D 50 km/hr, 12 km/hr
In the solution given it has taken 9 rather than 90 giving the wrong answer