Roshel left home at 11.35 a.m. and drove towards the suburb. 2 hours later, her mother left their home and drove towards the same suburb at 88 km/h. When the mother reached the suburb at 4.35 p.m., Roshel had another 6 km to travel. What was Roshel’s average speed? Express your answer in mixed number.
Time that the Roshel's mother started driving = 1.35 p.m.
Duration that Roshel's mother drove from 1.35 p.m. to 4.35 p.m. = 3 h

Distance that Roshel's mother travelled
= 3 x 88
= 264 km

Distance that Roshel travelled by the time her mother reached the city
= 264 - 6
= 258 km

Time that Roshel took to travel 258 km = 5 h

Roshel's average speed
= 258 ÷ 5
= 51³₅ km/h

Answer(s): 51³₅ km/h