City A and City B are 378 km apart. At 4.35 p.m., Justin is travelling at a uniform speed left City A for City B while Warren set off from City B to City A along the same road at a uniform speed, which was 7 km/h slower than that of Justin. The two met at 6.35 p.m.

1. Find the speed of Justin.
2. If Warren 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 Warren to travel from 4.35 p.m. to 6.35 p.m. = 2 h

Average speed of Justin and Warren
= 378 ÷ 2
= 189 km/h

Justin's speed
= (189 + 7) ÷ 2
= 196 ÷ 2 
= 98 km/h

(b)
Warren's speed
= 98 - 7
= 91 km/h

Distance that Warren travelled in 2 h
= 2 x 91
= 182 km

Remaining distance that Warren needed to travel
= 378 - 182
= 196 km

Time that Warren needed to reach his destination after the two met
= 196 ÷ 91
= 2¹⁴₉₁
= 2²₁₃ h

Answer(s): (a) 98 km/h; (b) 2²₁₃ h