Mrs Yang left home at 10 a.m. and drove towards the city. 1²₃ hour later, Mr Yang left the house and drove at an average speed of 93 km/h towards the city. When Mr Yang reached his destination at 3 p.m., Mrs Yang was 29 km away from the city. Find Mrs Yang’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
²₃ h = ²₃ x 60 = 40 min
1²₃ = 1 h 40 min

1 h 40 min after 10 a.m. = 11.40 a.m.

Time that Mr Yang left the house = 11.40 a.m.

Time that Mr Yang took from 11.40 a.m. to 3 p.m. to reach his destination = 3 h 20 min

1 min = ¹₆₀ h
20 min = ²⁰₆₀ h = ¹₃ h
3 h 20 min = 3¹₃ h

Distance that Mr Yang drove
= 3¹₃ x 93
= 310 km

Distance that Mrs Yang drove when Mr Yang reached
= 310 - 29 
= 281 km

Time that Mrs Yang took to travel from 10 a.m. to 3 p.m. = 5 h

Mrs Yang's average speed
= 281 ÷ 5
= 56¹₅ km/h

Answer(s): 56¹₅ km/h