Mrs Seow left home at 7 a.m. and drove towards the city. 2¹₃ hour later, Mr Seow left the house and drove at an average speed of 106 km/h towards the city. When Mr Seow reached his destination at 3 p.m., Mrs Seow was 27 km away from the city. Find Mrs Seow’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₃ h = ¹₃ x 60 = 20 min
2¹₃ = 2 h 20 min

2 h 20 min after 7 a.m. = 9.20 a.m.

Time that Mr Seow left the house = 9.20 a.m.

Time that Mr Seow took from 9.20 a.m. to 3 p.m. to reach his destination = 5 h 40 min

1 min = ¹₆₀ h
40 min = ⁴⁰₆₀ h = ²₃ h
5 h 40 min = 5²₃ h

Distance that Mr Seow drove
= 5²₃ x 106
= 600²₃ km

Distance that Mrs Seow drove when Mr Seow reached
= 600²₃ - 27 
= 573²₃ km

Time that Mrs Seow took to travel from 7 a.m. to 3 p.m. = 8 h

Mrs Seow's average speed
= 573²₃ ÷ 8
= 71¹⁷₂₄ km/h

Answer(s): 71¹⁷₂₄ km/h