Roshel left home at 11.50 a.m. and drove towards the seaside resort. 2 hours later, her younger sister left their home and drove towards the same seaside resort at 89 km/h. When the younger sister reached the seaside resort at 4.50 p.m., Roshel had another 5 km to travel. What was Roshel’s average speed? Express your answer in mixed number.
Time that the Roshel's younger sister started driving = 1.50 p.m.
Duration that Roshel's younger sister drove from 1.50 p.m. to 4.50 p.m. = 3 h

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

Distance that Roshel travelled by the time her younger sister reached the city
= 267 - 5
= 262 km

Time that Roshel took to travel 262 km = 5 h

Roshel's average speed
= 262 ÷ 5
= 52²₅ km/h

Answer(s): 52²₅ km/h