Fanny left home at 10.50 a.m. and drove towards the countryside. 3 hours later, her cousin left their home and drove towards the same countryside at 90 km/h. When the cousin reached the countryside at 6.50 p.m., Fanny had another 4 km to travel. What was Fanny’s average speed? Express your answer in mixed number.
Time that the Fanny's cousin started driving = 1.50 p.m.
Duration that Fanny's cousin drove from 1.50 p.m. to 6.50 p.m. = 5 h

Distance that Fanny's cousin travelled
= 5 x 90
= 450 km

Distance that Fanny travelled by the time her cousin reached the city
= 450 - 4
= 446 km

Time that Fanny took to travel 446 km = 8 h

Fanny's average speed
= 446 ÷ 8
= 55³₄ km/h

Answer(s): 55³₄ km/h