City M and City N is 300 km apart. Andy left City M for City N at 7.00 a.m. travelling at an average speed of 60 km/h. Wesley left City M later than Andy and caught up with him at 10.00 a.m. Wesley was travelling at a speed of 108 km/h.

1. At what time did Wesley leave City M?
2. How much later did Andy arrive in City N than Wesley? 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 Andy covered when Wesley caught up with Andy
= 3 x 60
= 180 km

Time that Wesley took to travel 180 km
= 180 ÷ 108
= 1²₃ h

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

Time that Wesley left City M:
1 h 40 min before 10.00 a.m. = 8.20 a.m.

(b)
Remaining distance that they had to cover to reach City N
= 300 - 180
= 120 km

Duration that Wesley had to travel before reaching City N
= 120 ÷ 108
= 1¹₉ h

Duration that Andy had to travel before reaching City N
= 120 ÷ 60
= 2 h

Duration that Andy took to arrive later than Wesley in City N
= 2 - 1¹₉
= ⁸₉ h

Answer(s): (a) 8.20 a.m.; (b) ⁸₉ h