Lucy left home at 11.25 a.m. and drove towards the suburb. 3 hours later, her cousin left their home and drove towards the same suburb at 99 km/h. When the cousin reached the suburb at 6.25 p.m., Lucy had another 4 km to travel. What was Lucy’s average speed? Express your answer in mixed number.
Time that the Lucy's cousin started driving = 2.25 p.m.
Duration that Lucy's cousin drove from 2.25 p.m. to 6.25 p.m. = 4 h

Distance that Lucy's cousin travelled
= 4 x 99
= 396 km

Distance that Lucy travelled by the time her cousin reached the city
= 396 - 4
= 392 km

Time that Lucy took to travel 392 km = 7 h

Lucy's average speed
= 392 ÷ 7
= 56 km/h

Answer(s): 56 km/h