City X and City Y are 595 km apart. At 5.31 p.m., Justin is travelling at a uniform speed left City X for City Y while Oliver set off from City Y to City X along the same road at a uniform speed, which was 7 km/h slower than that of Justin. The two met at 10.31 p.m.

1. Find the speed of Justin.
2. If Oliver continued to travel at the same speed, how long would it take for him to reach his destination after the two met? Express your answer in mixed number.

(a)
Time taken for Justin and Oliver to travel from 5.31 p.m. to 10.31 p.m. = 5 h

Average speed of Justin and Oliver
= 595 ÷ 5
= 119 km/h

Justin's speed
= (119 + 7) ÷ 2
= 126 ÷ 2 
= 63 km/h

(b)
Oliver's speed
= 63 - 7
= 56 km/h

Distance that Oliver travelled in 5 h
= 5 x 56
= 280 km

Remaining distance that Oliver needed to travel
= 595 - 280
= 315 km

Time that Oliver needed to reach his destination after the two met
= 315 ÷ 56
= 5³⁵₅₆
= 5⁵₈ h

Answer(s): (a) 63 km/h; (b) 5⁵₈ h