Cathy left home at 11.20 a.m. and drove towards the province. 2 hours later, her father left their home and drove towards the same province at 90 km/h. When the father reached the province at 5.20 p.m., Cathy had another 3 km to travel. What was Cathy’s average speed? Express your answer in mixed number.
Time that the Cathy's father started driving = 1.20 p.m.
Duration that Cathy's father drove from 1.20 p.m. to 5.20 p.m. = 4 h

Distance that Cathy's father travelled
= 4 x 90
= 360 km

Distance that Cathy travelled by the time her father reached the city
= 360 - 3
= 357 km

Time that Cathy took to travel 357 km = 6 h

Cathy's average speed
= 357 ÷ 6
= 59¹₂ km/h

Answer(s): 59¹₂ km/h