Tina left home at 10.30 a.m. and drove towards the seaside resort. 3 hours later, her mother left their home and drove towards the same seaside resort at 91 km/h. When the mother reached the seaside resort at 6.30 p.m., Tina had another 3 km to travel. What was Tina’s average speed? Express your answer in mixed number.
Time that the Tina's mother started driving = 1.30 p.m.
Duration that Tina's mother drove from 1.30 p.m. to 6.30 p.m. = 5 h

Distance that Tina's mother travelled
= 5 x 91
= 455 km

Distance that Tina travelled by the time her mother reached the city
= 455 - 3
= 452 km

Time that Tina took to travel 452 km = 8 h

Tina's average speed
= 452 ÷ 8
= 56¹₂ km/h

Answer(s): 56¹₂ km/h