Mrs Kong left home at 9 a.m. and drove towards the city. 1¹₂ hour later, Mr Kong left the house and drove at an average speed of 97 km/h towards the city. When Mr Kong reached his destination at 2 p.m., Mrs Kong was 12 km away from the city. Find Mrs Kong’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₂ h = ¹₂ x 60 = 30 min
1¹₂ = 1 h 30 min

1 h 30 min after 9 a.m. = 10.30 a.m.

Time that Mr Kong left the house = 10.30 a.m.

Time that Mr Kong took from 10.30 a.m. to 2 p.m. to reach his destination = 3 h 30 min

1 min = ¹₆₀ h
30 min = ³⁰₆₀ h = ¹₂ h
3 h 30 min = 3¹₂ h

Distance that Mr Kong drove
= 3¹₂ x 97
= 339¹₂ km

Distance that Mrs Kong drove when Mr Kong reached
= 339¹₂ - 12 
= 327¹₂ km

Time that Mrs Kong took to travel from 9 a.m. to 2 p.m. = 5 h

Mrs Kong's average speed
= 327¹₂ ÷ 5
= 65¹₂ km/h

Answer(s): 65¹₂ km/h