City D and City E are 330 km apart. At 2.38 p.m., Ben is travelling at a uniform speed left City D for City E while Riordan set off from City E to City D along the same road at a uniform speed, which was 9 km/h slower than that of Ben. The two met at 4.38 p.m.

1. Find the speed of Ben.
2. If Riordan 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 Ben and Riordan to travel from 2.38 p.m. to 4.38 p.m. = 2 h

Average speed of Ben and Riordan
= 330 ÷ 2
= 165 km/h

Ben's speed
= (165 + 9) ÷ 2
= 174 ÷ 2 
= 87 km/h

(b)
Riordan's speed
= 87 - 9
= 78 km/h

Distance that Riordan travelled in 2 h
= 2 x 78
= 156 km

Remaining distance that Riordan needed to travel
= 330 - 156
= 174 km

Time that Riordan needed to reach his destination after the two met
= 174 ÷ 78
= 2¹⁸₇₈
= 2³₁₃ h

Answer(s): (a) 87 km/h; (b) 2³₁₃ h