Gabby left home at 10.45 a.m. and drove towards the suburb. 3 hours later, her grandfather left their home and drove towards the same suburb at 96 km/h. When the grandfather reached the suburb at 6.45 p.m., Gabby had another 2 km to travel. What was Gabby’s average speed? Express your answer in mixed number.
Time that the Gabby's grandfather started driving = 1.45 p.m.
Duration that Gabby's grandfather drove from 1.45 p.m. to 6.45 p.m. = 5 h

Distance that Gabby's grandfather travelled
= 5 x 96
= 480 km

Distance that Gabby travelled by the time her grandfather reached the city
= 480 - 2
= 478 km

Time that Gabby took to travel 478 km = 8 h

Gabby's average speed
= 478 ÷ 8
= 59³₄ km/h

Answer(s): 59³₄ km/h