Raeann left home at 11.45 a.m. and drove towards the seaside resort. 3 hours later, her younger sister left their home and drove towards the same seaside resort at 86 km/h. When the younger sister reached the seaside resort at 7.45 p.m., Raeann had another 2 km to travel. What was Raeann’s average speed? Express your answer in mixed number.
Time that the Raeann's younger sister started driving = 2.45 p.m.
Duration that Raeann's younger sister drove from 2.45 p.m. to 7.45 p.m. = 5 h

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

Distance that Raeann travelled by the time her younger sister reached the city
= 430 - 2
= 428 km

Time that Raeann took to travel 428 km = 8 h

Raeann's average speed
= 428 ÷ 8
= 53¹₂ km/h

Answer(s): 53¹₂ km/h