City X and City Y are 588 km apart. At 3.53 p.m., Ryan is travelling at a uniform speed left City X for City Y while Luis 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 Ryan. The two met at 7.53 p.m.

1. Find the speed of Ryan.
2. If Luis 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 Ryan and Luis to travel from 3.53 p.m. to 7.53 p.m. = 4 h

Average speed of Ryan and Luis
= 588 ÷ 4
= 147 km/h

Ryan's speed
= (147 + 7) ÷ 2
= 154 ÷ 2 
= 77 km/h

(b)
Luis's speed
= 77 - 7
= 70 km/h

Distance that Luis travelled in 4 h
= 4 x 70
= 280 km

Remaining distance that Luis needed to travel
= 588 - 280
= 308 km

Time that Luis needed to reach his destination after the two met
= 308 ÷ 70
= 4²⁸₇₀
= 4²₅ h

Answer(s): (a) 77 km/h; (b) 4²₅ h