Victoria left home at 11.50 a.m. and drove towards the city. 2 hours later, her father left their home and drove towards the same city at 85 km/h. When the father reached the city at 5.50 p.m., Victoria had another 4 km to travel. What was Victoria’s average speed? Express your answer in mixed number.
Time that the Victoria's father started driving = 1.50 p.m.
Duration that Victoria's father drove from 1.50 p.m. to 5.50 p.m. = 4 h

Distance that Victoria's father travelled
= 4 x 85
= 340 km

Distance that Victoria travelled by the time her father reached the city
= 340 - 4
= 336 km

Time that Victoria took to travel 336 km = 6 h

Victoria's average speed
= 336 ÷ 6
= 56 km/h

Answer(s): 56 km/h