Usha left home at 10.10 a.m. and drove towards the campsite. 3 hours later, her younger sister left their home and drove towards the same campsite at 83 km/h. When the younger sister reached the campsite at 6.10 p.m., Usha had another 3 km to travel. What was Usha’s average speed? Express your answer in mixed number.
Time that the Usha's younger sister started driving = 1.10 p.m.
Duration that Usha's younger sister drove from 1.10 p.m. to 6.10 p.m. = 5 h

Distance that Usha's younger sister travelled
= 5 x 83
= 415 km

Distance that Usha travelled by the time her younger sister reached the city
= 415 - 3
= 412 km

Time that Usha took to travel 412 km = 8 h

Usha's average speed
= 412 ÷ 8
= 51¹₂ km/h

Answer(s): 51¹₂ km/h