Wendy left home at 11.20 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 4.20 p.m., Wendy had another 4 km to travel. What was Wendy’s average speed? Express your answer in mixed number.
Time that the Wendy's grandfather started driving = 1.20 p.m.
Duration that Wendy's grandfather drove from 1.20 p.m. to 4.20 p.m. = 3 h

Distance that Wendy's grandfather travelled
= 3 x 99
= 297 km

Distance that Wendy travelled by the time her grandfather reached the city
= 297 - 4
= 293 km

Time that Wendy took to travel 293 km = 5 h

Wendy's average speed
= 293 ÷ 5
= 58³₅ km/h

Answer(s): 58³₅ km/h