Mrs Song left home at 9 a.m. and drove towards the city. 2¹₆ hour later, Mr Song left the house and drove at an average speed of 108 km/h towards the city. When Mr Song reached his destination at 2 p.m., Mrs Song was 19 km away from the city. Find Mrs Song’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₆ h = ¹₆ x 60 = 10 min
2¹₆ = 2 h 10 min

2 h 10 min after 9 a.m. = 11.10 a.m.

Time that Mr Song left the house = 11.10 a.m.

Time that Mr Song took from 11.10 a.m. to 2 p.m. to reach his destination = 2 h 50 min

1 min = ¹₆₀ h
50 min = ⁵⁰₆₀ h = ⁵₆ h
2 h 50 min = 2⁵₆ h

Distance that Mr Song drove
= 2⁵₆ x 108
= 306 km

Distance that Mrs Song drove when Mr Song reached
= 306 - 19 
= 287 km

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

Mrs Song's average speed
= 287 ÷ 5
= 57²₅ km/h

Answer(s): 57²₅ km/h