City W and City X is 560 km apart. Nick left City W for City X at 7.00 a.m. travelling at an average speed of 80 km/h. Mark left City W later than Nick and caught up with him at 9.00 a.m. Mark was travelling at a speed of 96 km/h.

1. At what time did Mark leave City W?
2. How much later did Nick arrive in City X than Mark? 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 Nick covered when Mark caught up with Nick
= 2 x 80
= 160 km

Time that Mark took to travel 160 km
= 160 ÷ 96
= 1²₃ h

1 h = 60 min
²₃ h = ²₃ x 60 = 40 min
1²₃ h = 1 h 40 min

Time that Mark left City W:
1 h 40 min before 9.00 a.m. = 7.20 a.m.

(b)
Remaining distance that they had to cover to reach City X
= 560 - 160
= 400 km

Duration that Mark had to travel before reaching City X
= 400 ÷ 96
= 4¹₆ h

Duration that Nick had to travel before reaching City X
= 400 ÷ 80
= 5 h

Duration that Nick took to arrive later than Mark in City X
= 5 - 4¹₆
= ⁵₆ h

Answer(s): (a) 7.20 a.m.; (b) ⁵₆ h