Answer : 1. "140 kms"
Explanation :

Answer: A) 140 kms Explanation: It is given train X leave station A at 6:30 am, here it is asked to calculate the distance from A when the trains meet, theDistance traveled by train left at 6:30 am upto 7:40 am i.e. in 1 hr. 10 min. or 7/6 hours = 30 x 7/6 = 35 kmSo train leaving at 7:40 am will meet first train after covering a distance of 35 km. with relative speed of 40-30=10 km/hr.Hence time taken = 35/10 = 3.5 hours or 3 hours 30 minutesSo distance from A = Distance traveled by 2nd train in 3 hr. 30 min = 40 x 3.5 = 140 km.