City B and City C is 480 km apart. Neave left City B for City C at 9.00 a.m. travelling at an average speed of 60 km/h. Riordan left City B later than Neave and caught up with him at 12.00 p.m. Riordan was travelling at a speed of 80 km/h.

1. At what time did Riordan leave City B?
2. How much later did Neave arrive in City C than Riordan? Express your answer in h as a fraction or mixed number.

(a)
From 9.00 a.m. to 12.00 p.m. = 3 h

Distance that Neave covered when Riordan caught up with Neave
= 3 x 60
= 180 km

Time that Riordan took to travel 180 km
= 180 ÷ 80
= 2¹₄ h

1 h = 60 min
¹₄ h = ¹₄ x 60 = 15 min
2¹₄ h = 2 h 15 min

Time that Riordan left City B:
2 h 15 min before 12.00 p.m. = 9.45 a.m.

(b)
Remaining distance that they had to cover to reach City C
= 480 - 180
= 300 km

Duration that Riordan had to travel before reaching City C
= 300 ÷ 80
= 3³₄ h

Duration that Neave had to travel before reaching City C
= 300 ÷ 60
= 5 h

Duration that Neave took to arrive later than Riordan in City C
= 5 - 3³₄
= 1¹₄ h

Answer(s): (a) 9.45 a.m.; (b) 1¹₄ h