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

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

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

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

Duration that Bryan had to travel before reaching City D
= 400 ÷ 96
= 4¹₆ h

Duration that Mark had to travel before reaching City D
= 400 ÷ 80
= 5 h

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

Answer(s): (a) 7.20 a.m.; (b) ⁵₆ h