City D and City E is 420 km apart. Ian left City D for City E at 10.00 a.m. travelling at an average speed of 60 km/h. Brandon left City D later than Ian and caught up with him at 1.00 p.m. Brandon was travelling at a speed of 80 km/h.

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

(a)
From 10.00 a.m. to 1.00 p.m. = 3 h

Distance that Ian covered when Brandon caught up with Ian
= 3 x 60
= 180 km

Time that Brandon took to travel 180 km
= 180 ÷ 80
= 2¹₄ h

1 h = 60 min
¹₄ h = ¹₄ x 60 = 15 min
2¹₄ h = 2 h 15 min

Time that Brandon left City D:
2 h 15 min before 1.00 p.m. = 10.45 a.m.

(b)
Remaining distance that they had to cover to reach City E
= 420 - 180
= 240 km

Duration that Brandon had to travel before reaching City E
= 240 ÷ 80
= 3 h

Duration that Ian had to travel before reaching City E
= 240 ÷ 60
= 4 h

Duration that Ian took to arrive later than Brandon in City E
= 4 - 3
= 1 h

Answer(s): (a) 10.45 a.m.; (b) 1 h