Fiona left home at 11.45 a.m. and drove towards the city. 2 hours later, her younger sister left their home and drove towards the same city at 89 km/h. When the younger sister reached the city at 4.45 p.m., Fiona had another 2 km to travel. What was Fiona’s average speed? Express your answer in mixed number.
Time that the Fiona's younger sister started driving = 1.45 p.m.
Duration that Fiona's younger sister drove from 1.45 p.m. to 4.45 p.m. = 3 h

Distance that Fiona's younger sister travelled
= 3 x 89
= 267 km

Distance that Fiona travelled by the time her younger sister reached the city
= 267 - 2
= 265 km

Time that Fiona took to travel 265 km = 5 h

Fiona's average speed
= 265 ÷ 5
= 53 km/h

Answer(s): 53 km/h