Mrs Tan left home at 7 a.m. and drove towards the city. 2¹₂ hour later, Mr Tan left the house and drove at an average speed of 93 km/h towards the city. When Mr Tan reached his destination at 1 p.m., Mrs Tan was 24 km away from the city. Find Mrs Tan’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₂ h = ¹₂ x 60 = 30 min
2¹₂ = 2 h 30 min

2 h 30 min after 7 a.m. = 9.30 a.m.

Time that Mr Tan left the house = 9.30 a.m.

Time that Mr Tan took from 9.30 a.m. to 1 p.m. to reach his destination = 3 h 30 min

1 min = ¹₆₀ h
30 min = ³⁰₆₀ h = ¹₂ h
3 h 30 min = 3¹₂ h

Distance that Mr Tan drove
= 3¹₂ x 93
= 325¹₂ km

Distance that Mrs Tan drove when Mr Tan reached
= 325¹₂ - 24 
= 301¹₂ km

Time that Mrs Tan took to travel from 7 a.m. to 1 p.m. = 6 h

Mrs Tan's average speed
= 301¹₂ ÷ 6
= 50¹₄ km/h

Answer(s): 50¹₄ km/h