City N and City P is 325 km apart. Valen left City N for City P at 9.00 a.m. travelling at an average speed of 65 km/h. Albert left City N later than Valen and caught up with him at 11.00 a.m. Albert was travelling at a speed of 78 km/h.

1. At what time did Albert leave City N?
2. How much later did Valen arrive in City P than Albert? 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 Valen covered when Albert caught up with Valen
= 2 x 65
= 130 km

Time that Albert took to travel 130 km
= 130 ÷ 78
= 1²₃ h

1 h = 60 min
²₃ h = ²₃ x 60 = 40 min
1²₃ h = 1 h 40 min

Time that Albert left City N:
1 h 40 min before 11.00 a.m. = 9.20 a.m.

(b)
Remaining distance that they had to cover to reach City P
= 325 - 130
= 195 km

Duration that Albert had to travel before reaching City P
= 195 ÷ 78
= 2¹₂ h

Duration that Valen had to travel before reaching City P
= 195 ÷ 65
= 3 h

Duration that Valen took to arrive later than Albert in City P
= 3 - 2¹₂
= ¹₂ h

Answer(s): (a) 9.20 a.m.; (b) ¹₂ h