Nora left home at 11.35 a.m. and drove towards the countryside. 2 hours later, her mother left their home and drove towards the same countryside at 85 km/h. When the mother reached the countryside at 4.35 p.m., Nora had another 3 km to travel. What was Nora’s average speed? Express your answer in mixed number.
Time that the Nora's mother started driving = 1.35 p.m.
Duration that Nora's mother drove from 1.35 p.m. to 4.35 p.m. = 3 h

Distance that Nora's mother travelled
= 3 x 85
= 255 km

Distance that Nora travelled by the time her mother reached the city
= 255 - 3
= 252 km

Time that Nora took to travel 252 km = 5 h

Nora's average speed
= 252 ÷ 5
= 50²₅ km/h

Answer(s): 50²₅ km/h