City P and City Q are 480 km apart. At 6.10 p.m., Andy is travelling at a uniform speed left City P for City Q while Luke set off from City Q to City P along the same road at a uniform speed, which was 12 km/h slower than that of Andy. The two met at 10.10 p.m.

1. Find the speed of Andy.
2. If Luke 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 Andy and Luke to travel from 6.10 p.m. to 10.10 p.m. = 4 h

Average speed of Andy and Luke
= 480 ÷ 4
= 120 km/h

Andy's speed
= (120 + 12) ÷ 2
= 132 ÷ 2 
= 66 km/h

(b)
Luke's speed
= 66 - 12
= 54 km/h

Distance that Luke travelled in 4 h
= 4 x 54
= 216 km

Remaining distance that Luke needed to travel
= 480 - 216
= 264 km

Time that Luke needed to reach his destination after the two met
= 264 ÷ 54
= 4⁴⁸₅₄
= 4⁸₉ h

Answer(s): (a) 66 km/h; (b) 4⁸₉ h