Mrs Lin left home at 8 a.m. and drove towards the city. 1¹₃ hour later, Mr Lin left the house and drove at an average speed of 104 km/h towards the city. When Mr Lin reached his destination at 1 p.m., Mrs Lin was 22 km away from the city. Find Mrs Lin’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 8 a.m. = 9.20 a.m.

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

Time that Mr Lin took from 9.20 a.m. to 1 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 Lin drove
= 3²₃ x 104
= 381¹₃ km

Distance that Mrs Lin drove when Mr Lin reached
= 381¹₃ - 22 
= 359¹₃ km

Time that Mrs Lin took to travel from 8 a.m. to 1 p.m. = 5 h

Mrs Lin's average speed
= 359¹₃ ÷ 5
= 71¹³₁₅ km/h

Answer(s): 71¹³₁₅ km/h