Emily left home at 11.55 a.m. and drove towards the suburb. 2 hours later, her grandfather left their home and drove towards the same suburb at 99 km/h. When the grandfather reached the suburb at 5.55 p.m., Emily had another 3 km to travel. What was Emily’s average speed? Express your answer in mixed number.
Time that the Emily's grandfather started driving = 1.55 p.m.
Duration that Emily's grandfather drove from 1.55 p.m. to 5.55 p.m. = 4 h

Distance that Emily's grandfather travelled
= 4 x 99
= 396 km

Distance that Emily travelled by the time her grandfather reached the city
= 396 - 3
= 393 km

Time that Emily took to travel 393 km = 6 h

Emily's average speed
= 393 ÷ 6
= 65¹₂ km/h

Answer(s): 65¹₂ km/h