Natalie left home at 11.50 a.m. and drove towards the province. 3 hours later, her grandfather left their home and drove towards the same province at 97 km/h. When the grandfather reached the province at 7.50 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 grandfather started driving = 2.50 p.m.
Duration that Natalie's grandfather drove from 2.50 p.m. to 7.50 p.m. = 5 h

Distance that Natalie's grandfather travelled
= 5 x 97
= 485 km

Distance that Natalie travelled by the time her grandfather reached the city
= 485 - 5
= 480 km

Time that Natalie took to travel 480 km = 8 h

Natalie's average speed
= 480 ÷ 8
= 60 km/h

Answer(s): 60 km/h