Emma left home at 11.25 a.m. and drove towards the province. 3 hours later, her mother left their home and drove towards the same province at 90 km/h. When the mother reached the province at 6.25 p.m., Emma had another 3 km to travel. What was Emma’s average speed? Express your answer in mixed number.
Time that the Emma's mother started driving = 2.25 p.m.
Duration that Emma's mother drove from 2.25 p.m. to 6.25 p.m. = 4 h

Distance that Emma's mother travelled
= 4 x 90
= 360 km

Distance that Emma travelled by the time her mother reached the city
= 360 - 3
= 357 km

Time that Emma took to travel 357 km = 7 h

Emma's average speed
= 357 ÷ 7
= 51 km/h

Answer(s): 51 km/h