Two cars A and B having average speeds of 30 and 40 mph resp

Two cars, A and B, having average speeds of 30 and 40 mph, respectively are 280 miles apart they start moving towards each other at 3pm, At what time will they meet?

30x+40x=280
70x=280
x=280/70
x=4 hours.
3+4=7 pm. they will meet.