Julie left home at 11.30 a.m. and drove towards the city. 2 hours later, her older sister left their home and drove towards the same city at 89 km/h. When the older sister reached the city at 4.30 p.m., Julie had another 4 km to travel. What was Julie’s average speed? Express your answer in mixed number.
Time that the Julie's older sister started driving = 1.30 p.m.
Duration that Julie's older sister drove from 1.30 p.m. to 4.30 p.m. = 3 h

Distance that Julie's older sister travelled
= 3 x 89
= 267 km

Distance that Julie travelled by the time her older sister reached the city
= 267 - 4
= 263 km

Time that Julie took to travel 263 km = 5 h

Julie's average speed
= 263 ÷ 5
= 52³₅ km/h

Answer(s): 52³₅ km/h