Emily left home at 11.20 a.m. and drove towards the campsite. 2 hours later, her grandfather left their home and drove towards the same campsite at 90 km/h. When the grandfather reached the campsite at 4.20 p.m., Emily had another 5 km to travel. What was Emily’s average speed? Express your answer in mixed number.
Time that the Emily's grandfather started driving = 1.20 p.m.
Duration that Emily's grandfather drove from 1.20 p.m. to 4.20 p.m. = 3 h

Distance that Emily's grandfather travelled
= 3 x 90
= 270 km

Distance that Emily travelled by the time her grandfather reached the city
= 270 - 5
= 265 km

Time that Emily took to travel 265 km = 5 h

Emily's average speed
= 265 ÷ 5
= 53 km/h

Answer(s): 53 km/h