City E and City F is 350 km apart. Liam left City E for City F at 9.00 a.m. travelling at an average speed of 70 km/h. Sean left City E later than Liam and caught up with him at 11.00 a.m. Sean was travelling at a speed of 80 km/h.

1. At what time did Sean leave City E?
2. How much later did Liam arrive in City F than Sean? 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 Liam covered when Sean caught up with Liam
= 2 x 70
= 140 km

Time that Sean took to travel 140 km
= 140 ÷ 80
= 1³₄ h

1 h = 60 min
³₄ h = ³₄ x 60 = 45 min
1³₄ h = 1 h 45 min

Time that Sean left City E:
1 h 45 min before 11.00 a.m. = 9.15 a.m.

(b)
Remaining distance that they had to cover to reach City F
= 350 - 140
= 210 km

Duration that Sean had to travel before reaching City F
= 210 ÷ 80
= 2⁵₈ h

Duration that Liam had to travel before reaching City F
= 210 ÷ 70
= 3 h

Duration that Liam took to arrive later than Sean in City F
= 3 - 2⁵₈
= ³₈ h

Answer(s): (a) 9.15 a.m.; (b) ³₈ h