Fanny left home at 10.10 a.m. and drove towards the countryside. 3 hours later, her younger sister left their home and drove towards the same countryside at 86 km/h. When the younger sister reached the countryside at 6.10 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 younger sister started driving = 1.10 p.m.
Duration that Fanny's younger sister drove from 1.10 p.m. to 6.10 p.m. = 5 h

Distance that Fanny's younger sister travelled
= 5 x 86
= 430 km

Distance that Fanny travelled by the time her younger sister reached the city
= 430 - 4
= 426 km

Time that Fanny took to travel 426 km = 8 h

Fanny's average speed
= 426 ÷ 8
= 53¹₄ km/h

Answer(s): 53¹₄ km/h