City Y and City Z is 560 km apart. Vincent left City Y for City Z at 7.00 a.m. travelling at an average speed of 80 km/h. Andy left City Y later than Vincent and caught up with him at 10.00 a.m. Andy was travelling at a speed of 96 km/h.

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

(a)
From 7.00 a.m. to 10.00 a.m. = 3 h

Distance that Vincent covered when Andy caught up with Vincent
= 3 x 80
= 240 km

Time that Andy took to travel 240 km
= 240 ÷ 96
= 2¹₂ h

1 h = 60 min
¹₂ h = ¹₂ x 60 = 30 min
2¹₂ h = 2 h 30 min

Time that Andy left City Y:
2 h 30 min before 10.00 a.m. = 7.30 a.m.

(b)
Remaining distance that they had to cover to reach City Z
= 560 - 240
= 320 km

Duration that Andy had to travel before reaching City Z
= 320 ÷ 96
= 3¹₃ h

Duration that Vincent had to travel before reaching City Z
= 320 ÷ 80
= 4 h

Duration that Vincent took to arrive later than Andy in City Z
= 4 - 3¹₃
= ²₃ h

Answer(s): (a) 7.30 a.m.; (b) ²₃ h