Mrs Kok left home at 9 a.m. and drove towards the city. 1²₃ hour later, Mr Kok left the house and drove at an average speed of 95 km/h towards the city. When Mr Kok reached his destination at 1 p.m., Mrs Kok was 20 km away from the city. Find Mrs Kok’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
²₃ h = ²₃ x 60 = 40 min
1²₃ = 1 h 40 min

1 h 40 min after 9 a.m. = 10.40 a.m.

Time that Mr Kok left the house = 10.40 a.m.

Time that Mr Kok took from 10.40 a.m. to 1 p.m. to reach his destination = 2 h 20 min

1 min = ¹₆₀ h
20 min = ²⁰₆₀ h = ¹₃ h
2 h 20 min = 2¹₃ h

Distance that Mr Kok drove
= 2¹₃ x 95
= 221²₃ km

Distance that Mrs Kok drove when Mr Kok reached
= 221²₃ - 20 
= 201²₃ km

Time that Mrs Kok took to travel from 9 a.m. to 1 p.m. = 4 h

Mrs Kok's average speed
= 201²₃ ÷ 4
= 50⁵₁₂ km/h

Answer(s): 50⁵₁₂ km/h