City C and City D is 630 km apart. Elijah left City C for City D at 7.00 a.m. travelling at an average speed of 70 km/h. Vincent left City C later than Elijah and caught up with him at 11.00 a.m. Vincent was travelling at a speed of 112 km/h.

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

(a)
From 7.00 a.m. to 11.00 a.m. = 4 h

Distance that Elijah covered when Vincent caught up with Elijah
= 4 x 70
= 280 km

Time that Vincent took to travel 280 km
= 280 ÷ 112
= 2¹₂ h

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

Time that Vincent left City C:
2 h 30 min before 11.00 a.m. = 8.30 a.m.

(b)
Remaining distance that they had to cover to reach City D
= 630 - 280
= 350 km

Duration that Vincent had to travel before reaching City D
= 350 ÷ 112
= 3¹₈ h

Duration that Elijah had to travel before reaching City D
= 350 ÷ 70
= 5 h

Duration that Elijah took to arrive later than Vincent in City D
= 5 - 3¹₈
= 1⁷₈ h

Answer(s): (a) 8.30 a.m.; (b) 1⁷₈ h