Mrs Seah left home at 9 a.m. and drove towards the city. 2¹₃ hour later, Mr Seah left the house and drove at an average speed of 101 km/h towards the city. When Mr Seah reached his destination at 3 p.m., Mrs Seah was 17 km away from the city. Find Mrs Seah’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 9 a.m. = 11.20 a.m.

Time that Mr Seah left the house = 11.20 a.m.

Time that Mr Seah took from 11.20 a.m. to 3 p.m. to reach his destination = 3 h 40 min

1 min = ¹₆₀ h
40 min = ⁴⁰₆₀ h = ²₃ h
3 h 40 min = 3²₃ h

Distance that Mr Seah drove
= 3²₃ x 101
= 370¹₃ km

Distance that Mrs Seah drove when Mr Seah reached
= 370¹₃ - 17 
= 353¹₃ km

Time that Mrs Seah took to travel from 9 a.m. to 3 p.m. = 6 h

Mrs Seah's average speed
= 353¹₃ ÷ 6
= 58⁸₉ km/h

Answer(s): 58⁸₉ km/h