City U and City V is 320 km apart. Oscar left City U for City V at 7.00 a.m. travelling at an average speed of 64 km/h. Michael left City U later than Oscar and caught up with him at 9.00 a.m. Michael was travelling at a speed of 96 km/h.

1. At what time did Michael leave City U?
2. How much later did Oscar arrive in City V than Michael? Express your answer in h as a fraction or mixed number.

(a)
From 7.00 a.m. to 9.00 a.m. = 2 h

Distance that Oscar covered when Michael caught up with Oscar
= 2 x 64
= 128 km

Time that Michael took to travel 128 km
= 128 ÷ 96
= 1¹₃ h

1 h = 60 min
¹₃ h = ¹₃ x 60 = 20 min
1¹₃ h = 1 h 20 min

Time that Michael left City U:
1 h 20 min before 9.00 a.m. = 7.40 a.m.

(b)
Remaining distance that they had to cover to reach City V
= 320 - 128
= 192 km

Duration that Michael had to travel before reaching City V
= 192 ÷ 96
= 2 h

Duration that Oscar had to travel before reaching City V
= 192 ÷ 64
= 3 h

Duration that Oscar took to arrive later than Michael in City V
= 3 - 2
= 1 h

Answer(s): (a) 7.40 a.m.; (b) 1 h