Mrs Chua left home at 10 a.m. and drove towards the city. 1¹₄ hour later, Mr Chua left the house and drove at an average speed of 103 km/h towards the city. When Mr Chua reached his destination at 3 p.m., Mrs Chua was 28 km away from the city. Find Mrs Chua’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₄ h = ¹₄ x 60 = 15 min
1¹₄ = 1 h 15 min

1 h 15 min after 10 a.m. = 11.15 a.m.

Time that Mr Chua left the house = 11.15 a.m.

Time that Mr Chua took from 11.15 a.m. to 3 p.m. to reach his destination = 3 h 45 min

1 min = ¹₆₀ h
45 min = ⁴⁵₆₀ h = ³₄ h
3 h 45 min = 3³₄ h

Distance that Mr Chua drove
= 3³₄ x 103
= 386¹₄ km

Distance that Mrs Chua drove when Mr Chua reached
= 386¹₄ - 28 
= 358¹₄ km

Time that Mrs Chua took to travel from 10 a.m. to 3 p.m. = 5 h

Mrs Chua's average speed
= 358¹₄ ÷ 5
= 71¹³₂₀ km/h

Answer(s): 71¹³₂₀ km/h