Mrs Ee left home at 7 a.m. and drove towards the city. 1¹₃ hour later, Mr Ee left the house and drove at an average speed of 84 km/h towards the city. When Mr Ee reached his destination at 3 p.m., Mrs Ee was 20 km away from the city. Find Mrs Ee’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₃ h = ¹₃ x 60 = 20 min
1¹₃ = 1 h 20 min

1 h 20 min after 7 a.m. = 8.20 a.m.

Time that Mr Ee left the house = 8.20 a.m.

Time that Mr Ee took from 8.20 a.m. to 3 p.m. to reach his destination = 6 h 40 min

1 min = ¹₆₀ h
40 min = ⁴⁰₆₀ h = ²₃ h
6 h 40 min = 6²₃ h

Distance that Mr Ee drove
= 6²₃ x 84
= 560 km

Distance that Mrs Ee drove when Mr Ee reached
= 560 - 20 
= 540 km

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

Mrs Ee's average speed
= 540 ÷ 8
= 67¹₂ km/h

Answer(s): 67¹₂ km/h