Zoe left home at 11.55 a.m. and drove towards the province. 2 hours later, her grandfather left their home and drove towards the same province at 97 km/h. When the grandfather reached the province at 6.55 p.m., Zoe had another 2 km to travel. What was Zoe’s average speed? Express your answer in mixed number.
Time that the Zoe's grandfather started driving = 1.55 p.m.
Duration that Zoe's grandfather drove from 1.55 p.m. to 6.55 p.m. = 5 h

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

Distance that Zoe travelled by the time her grandfather reached the city
= 485 - 2
= 483 km

Time that Zoe took to travel 483 km = 7 h

Zoe's average speed
= 483 ÷ 7
= 69 km/h

Answer(s): 69 km/h