City W and City X is 320 km apart. Michael left City W for City X at 11.00 a.m. travelling at an average speed of 64 km/h. Andy left City W later than Michael and caught up with him at 2.00 p.m. Andy was travelling at a speed of 72 km/h.

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

(a)
From 11.00 a.m. to 2.00 p.m. = 3 h

Distance that Michael covered when Andy caught up with Michael
= 3 x 64
= 192 km

Time that Andy took to travel 192 km
= 192 ÷ 72
= 2²₃ h

1 h = 60 min
²₃ h = ²₃ x 60 = 40 min
2²₃ h = 2 h 40 min

Time that Andy left City W:
2 h 40 min before 2.00 p.m. = 11.20 a.m.

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

Duration that Andy had to travel before reaching City X
= 128 ÷ 72
= 1⁷₉ h

Duration that Michael had to travel before reaching City X
= 128 ÷ 64
= 2 h

Duration that Michael took to arrive later than Andy in City X
= 2 - 1⁷₉
= ²₉ h

Answer(s): (a) 11.20 a.m.; (b) ²₉ h