Sarah left home at 10.20 a.m. and drove towards the town. 3 hours later, her older sister left their home and drove towards the same town at 92 km/h. When the older sister reached the town at 6.20 p.m., Sarah had another 2 km to travel. What was Sarah’s average speed? Express your answer in mixed number.
Time that the Sarah's older sister started driving = 1.20 p.m.
Duration that Sarah's older sister drove from 1.20 p.m. to 6.20 p.m. = 5 h

Distance that Sarah's older sister travelled
= 5 x 92
= 460 km

Distance that Sarah travelled by the time her older sister reached the city
= 460 - 2
= 458 km

Time that Sarah took to travel 458 km = 8 h

Sarah's average speed
= 458 ÷ 8
= 57¹₄ km/h

Answer(s): 57¹₄ km/h