City R and City S are 375 km apart. At 1.56 p.m., John is travelling at a uniform speed left City R for City S while Japheth set off from City S to City R along the same road at a uniform speed, which was 11 km/h slower than that of John. The two met at 4.56 p.m.

1. Find the speed of John.
2. If Japheth 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 John and Japheth to travel from 1.56 p.m. to 4.56 p.m. = 3 h

Average speed of John and Japheth
= 375 ÷ 3
= 125 km/h

John's speed
= (125 + 11) ÷ 2
= 136 ÷ 2 
= 68 km/h

(b)
Japheth's speed
= 68 - 11
= 57 km/h

Distance that Japheth travelled in 3 h
= 3 x 57
= 171 km

Remaining distance that Japheth needed to travel
= 375 - 171
= 204 km

Time that Japheth needed to reach his destination after the two met
= 204 ÷ 57
= 3³³₅₇
= 3¹¹₁₉ h

Answer(s): (a) 68 km/h; (b) 3¹¹₁₉ h