Gabby left home at 11.35 a.m. and drove towards the city. 2 hours later, her father left their home and drove towards the same city at 86 km/h. When the father reached the city at 6.35 p.m., Gabby had another 3 km to travel. What was Gabby’s average speed? Express your answer in mixed number.
Time that the Gabby's father started driving = 1.35 p.m.
Duration that Gabby's father drove from 1.35 p.m. to 6.35 p.m. = 5 h

Distance that Gabby's father travelled
= 5 x 86
= 430 km

Distance that Gabby travelled by the time her father reached the city
= 430 - 3
= 427 km

Time that Gabby took to travel 427 km = 7 h

Gabby's average speed
= 427 ÷ 7
= 61 km/h

Answer(s): 61 km/h