Ivory left home at 11.10 a.m. and drove towards the town. 2 hours later, her auntie left their home and drove towards the same town at 86 km/h. When the auntie reached the town at 4.10 p.m., Ivory had another 3 km to travel. What was Ivory’s average speed? Express your answer in mixed number.
Time that the Ivory's auntie started driving = 1.10 p.m.
Duration that Ivory's auntie drove from 1.10 p.m. to 4.10 p.m. = 3 h

Distance that Ivory's auntie travelled
= 3 x 86
= 258 km

Distance that Ivory travelled by the time her auntie reached the city
= 258 - 3
= 255 km

Time that Ivory took to travel 255 km = 5 h

Ivory's average speed
= 255 ÷ 5
= 51 km/h

Answer(s): 51 km/h