City D and City E is 378 km apart. Dylan left City D for City E at 9.00 a.m. travelling at an average speed of 63 km/h. Eric left City D later than Dylan and caught up with him at 11.00 a.m. Eric was travelling at a speed of 72 km/h.

1. At what time did Eric leave City D?
2. How much later did Dylan arrive in City E than Eric? 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 Dylan covered when Eric caught up with Dylan
= 2 x 63
= 126 km

Time that Eric took to travel 126 km
= 126 ÷ 72
= 1³₄ h

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

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

(b)
Remaining distance that they had to cover to reach City E
= 378 - 126
= 252 km

Duration that Eric had to travel before reaching City E
= 252 ÷ 72
= 3¹₂ h

Duration that Dylan had to travel before reaching City E
= 252 ÷ 63
= 4 h

Duration that Dylan took to arrive later than Eric in City E
= 4 - 3¹₂
= ¹₂ h

Answer(s): (a) 9.15 a.m.; (b) ¹₂ h