Mrs Loh left home at 9 a.m. and drove towards the city. 1¹₆ hour later, Mr Loh left the house and drove at an average speed of 103 km/h towards the city. When Mr Loh reached his destination at 1 p.m., Mrs Loh was 21 km away from the city. Find Mrs Loh’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₆ h = ¹₆ x 60 = 10 min
1¹₆ = 1 h 10 min

1 h 10 min after 9 a.m. = 10.10 a.m.

Time that Mr Loh left the house = 10.10 a.m.

Time that Mr Loh took from 10.10 a.m. to 1 p.m. to reach his destination = 2 h 50 min

1 min = ¹₆₀ h
50 min = ⁵⁰₆₀ h = ⁵₆ h
2 h 50 min = 2⁵₆ h

Distance that Mr Loh drove
= 2⁵₆ x 103
= 291⁵₆ km

Distance that Mrs Loh drove when Mr Loh reached
= 291⁵₆ - 21 
= 270⁵₆ km

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

Mrs Loh's average speed
= 270⁵₆ ÷ 4
= 67¹⁷₂₄ km/h

Answer(s): 67¹⁷₂₄ km/h