3. The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 km in 4 hours, then the speed of the first train is:
A. 87.5 km/hr
B. 84 km/hr
C. 70 km/hr
D. 75 km/hr
3. The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 km in 4 hours, then the speed of the first train is:
A. 87.5 km/hr
B. 84 km/hr
C. 70 km/hr
D. 75 km/hr