City K and City L is 420 km apart. Seth left City K for City L at 10.00 a.m. travelling at an average speed of 70 km/h. Jeremy left City K later than Seth and caught up with him at 12.00 p.m. Jeremy was travelling at a speed of 105 km/h.

1. At what time did Jeremy leave City K?
2. How much later did Seth arrive in City L than Jeremy? Express your answer in h as a fraction or mixed number.

(a)
From 10.00 a.m. to 12.00 p.m. = 2 h

Distance that Seth covered when Jeremy caught up with Seth
= 2 x 70
= 140 km

Time that Jeremy took to travel 140 km
= 140 ÷ 105
= 1¹₃ h

1 h = 60 min
¹₃ h = ¹₃ x 60 = 20 min
1¹₃ h = 1 h 20 min

Time that Jeremy left City K:
1 h 20 min before 12.00 p.m. = 10.40 a.m.

(b)
Remaining distance that they had to cover to reach City L
= 420 - 140
= 280 km

Duration that Jeremy had to travel before reaching City L
= 280 ÷ 105
= 2²₃ h

Duration that Seth had to travel before reaching City L
= 280 ÷ 70
= 4 h

Duration that Seth took to arrive later than Jeremy in City L
= 4 - 2²₃
= 1¹₃ h

Answer(s): (a) 10.40 a.m.; (b) 1¹₃ h