(c) Let the speed of the cars be x km/h and ykm/h, respectively. Their relative speeds when they are moving in same direction = (x – y) km/h. Their relative speeds when they are in opposite directions = (x + y) km/h. Now, 7
0
x+y
=1orx+y=70 ..... (i) and
70
(x−y)
=7orx–y=10 ..... (ii)Solving (i) and (ii), we have x = 40 km/h and y = 30 km/h.