City L and City M are 520 km apart. At 6.44 p.m., Charlie is travelling at a uniform speed left City L for City M while Reggie set off from City M to City L along the same road at a uniform speed, which was 10 km/h slower than that of Charlie. The two met at 10.44 p.m.

1. Find the speed of Charlie.
2. If Reggie 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 Charlie and Reggie to travel from 6.44 p.m. to 10.44 p.m. = 4 h

Average speed of Charlie and Reggie
= 520 ÷ 4
= 130 km/h

Charlie's speed
= (130 + 10) ÷ 2
= 140 ÷ 2 
= 70 km/h

(b)
Reggie's speed
= 70 - 10
= 60 km/h

Distance that Reggie travelled in 4 h
= 4 x 60
= 240 km

Remaining distance that Reggie needed to travel
= 520 - 240
= 280 km

Time that Reggie needed to reach his destination after the two met
= 280 ÷ 60
= 4⁴⁰₆₀
= 4²₃ h

Answer(s): (a) 70 km/h; (b) 4²₃ h