Abi left home at 10.40 a.m. and drove towards the countryside. 3 hours later, her younger sister left their home and drove towards the same countryside at 92 km/h. When the younger sister reached the countryside at 5.40 p.m., Abi had another 4 km to travel. What was Abi’s average speed? Express your answer in mixed number.
Time that the Abi's younger sister started driving = 1.40 p.m.
Duration that Abi's younger sister drove from 1.40 p.m. to 5.40 p.m. = 4 h

Distance that Abi's younger sister travelled
= 4 x 92
= 368 km

Distance that Abi travelled by the time her younger sister reached the city
= 368 - 4
= 364 km

Time that Abi took to travel 364 km = 7 h

Abi's average speed
= 364 ÷ 7
= 52 km/h

Answer(s): 52 km/h