City V and City W are 600 km apart. At 6.28 p.m., Riordan is travelling at a uniform speed left City V for City W while Rael set off from City W to City V along the same road at a uniform speed, which was 10 km/h slower than that of Riordan. The two met at 11.28 p.m.

1. Find the speed of Riordan.
2. If Rael 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 Riordan and Rael to travel from 6.28 p.m. to 11.28 p.m. = 5 h

Average speed of Riordan and Rael
= 600 ÷ 5
= 120 km/h

Riordan's speed
= (120 + 10) ÷ 2
= 130 ÷ 2 
= 65 km/h

(b)
Rael's speed
= 65 - 10
= 55 km/h

Distance that Rael travelled in 5 h
= 5 x 55
= 275 km

Remaining distance that Rael needed to travel
= 600 - 275
= 325 km

Time that Rael needed to reach his destination after the two met
= 325 ÷ 55
= 5⁵⁰₅₅
= 5¹⁰₁₁ h

Answer(s): (a) 65 km/h; (b) 5¹⁰₁₁ h