Mrs Teo left home at 7 a.m. and drove towards the city. 2³₄ hour later, Mr Teo left the house and drove at an average speed of 107 km/h towards the city. When Mr Teo reached his destination at 1 p.m., Mrs Teo was 18 km away from the city. Find Mrs Teo’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
³₄ h = ³₄ x 60 = 45 min
2³₄ = 2 h 45 min

2 h 45 min after 7 a.m. = 9.45 a.m.

Time that Mr Teo left the house = 9.45 a.m.

Time that Mr Teo took from 9.45 a.m. to 1 p.m. to reach his destination = 3 h 15 min

1 min = ¹₆₀ h
15 min = ¹⁵₆₀ h = ¹₄ h
3 h 15 min = 3¹₄ h

Distance that Mr Teo drove
= 3¹₄ x 107
= 347³₄ km

Distance that Mrs Teo drove when Mr Teo reached
= 347³₄ - 18 
= 329³₄ km

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

Mrs Teo's average speed
= 329³₄ ÷ 6
= 54²³₂₄ km/h

Answer(s): 54²³₂₄ km/h