City C and City D are 351 km apart. At 4.23 p.m., Japheth is travelling at a uniform speed left City C for City D while Asher set off from City D to City C along the same road at a uniform speed, which was 9 km/h slower than that of Japheth. The two met at 7.23 p.m.

1. Find the speed of Japheth.
2. If Asher 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 Japheth and Asher to travel from 4.23 p.m. to 7.23 p.m. = 3 h

Average speed of Japheth and Asher
= 351 ÷ 3
= 117 km/h

Japheth's speed
= (117 + 9) ÷ 2
= 126 ÷ 2 
= 63 km/h

(b)
Asher's speed
= 63 - 9
= 54 km/h

Distance that Asher travelled in 3 h
= 3 x 54
= 162 km

Remaining distance that Asher needed to travel
= 351 - 162
= 189 km

Time that Asher needed to reach his destination after the two met
= 189 ÷ 54
= 3²⁷₅₄
= 3¹₂ h

Answer(s): (a) 63 km/h; (b) 3¹₂ h