Cindy left home at 10.55 a.m. and drove towards the seaside resort. 3 hours later, her auntie left their home and drove towards the same seaside resort at 84 km/h. When the auntie reached the seaside resort at 6.55 p.m., Cindy had another 2 km to travel. What was Cindy’s average speed? Express your answer in mixed number.
Time that the Cindy's auntie started driving = 1.55 p.m.
Duration that Cindy's auntie drove from 1.55 p.m. to 6.55 p.m. = 5 h

Distance that Cindy's auntie travelled
= 5 x 84
= 420 km

Distance that Cindy travelled by the time her auntie reached the city
= 420 - 2
= 418 km

Time that Cindy took to travel 418 km = 8 h

Cindy's average speed
= 418 ÷ 8
= 52¹₄ km/h

Answer(s): 52¹₄ km/h