Natalie left home at 11.25 a.m. and drove towards the countryside. 2 hours later, her father left their home and drove towards the same countryside at 97 km/h. When the father reached the countryside at 4.25 p.m., Natalie had another 5 km to travel. What was Natalie’s average speed? Express your answer in mixed number.
Time that the Natalie's father started driving = 1.25 p.m.
Duration that Natalie's father drove from 1.25 p.m. to 4.25 p.m. = 3 h

Distance that Natalie's father travelled
= 3 x 97
= 291 km

Distance that Natalie travelled by the time her father reached the city
= 291 - 5
= 286 km

Time that Natalie took to travel 286 km = 5 h

Natalie's average speed
= 286 ÷ 5
= 57¹₅ km/h

Answer(s): 57¹₅ km/h