City H and City J is 378 km apart. Billy left City H for City J at 9.00 a.m. travelling at an average speed of 63 km/h. Nick left City H later than Billy and caught up with him at 11.00 a.m. Nick was travelling at a speed of 84 km/h.

1. At what time did Nick leave City H?
2. How much later did Billy arrive in City J than Nick? Express your answer in h as a fraction or mixed number.

(a)
From 9.00 a.m. to 11.00 a.m. = 2 h

Distance that Billy covered when Nick caught up with Billy
= 2 x 63
= 126 km

Time that Nick took to travel 126 km
= 126 ÷ 84
= 1¹₂ h

1 h = 60 min
¹₂ h = ¹₂ x 60 = 30 min
1¹₂ h = 1 h 30 min

Time that Nick left City H:
1 h 30 min before 11.00 a.m. = 9.30 a.m.

(b)
Remaining distance that they had to cover to reach City J
= 378 - 126
= 252 km

Duration that Nick had to travel before reaching City J
= 252 ÷ 84
= 3 h

Duration that Billy had to travel before reaching City J
= 252 ÷ 63
= 4 h

Duration that Billy took to arrive later than Nick in City J
= 4 - 3
= 1 h

Answer(s): (a) 9.30 a.m.; (b) 1 h