Fiona left home at 11.50 a.m. and drove towards the campsite. 3 hours later, her older brother left their home and drove towards the same campsite at 89 km/h. When the older brother reached the campsite at 6.50 p.m., Fiona had another 6 km to travel. What was Fiona’s average speed? Express your answer in mixed number.
Time that the Fiona's older brother started driving = 2.50 p.m.
Duration that Fiona's older brother drove from 2.50 p.m. to 6.50 p.m. = 4 h

Distance that Fiona's older brother travelled
= 4 x 89
= 356 km

Distance that Fiona travelled by the time her older brother reached the city
= 356 - 6
= 350 km

Time that Fiona took to travel 350 km = 7 h

Fiona's average speed
= 350 ÷ 7
= 50 km/h

Answer(s): 50 km/h