Zoe left home at 11.35 a.m. and drove towards the countryside. 2 hours later, her younger sister left their home and drove towards the same countryside at 97 km/h. When the younger sister reached the countryside at 4.35 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 younger sister started driving = 1.35 p.m.
Duration that Zoe's younger sister drove from 1.35 p.m. to 4.35 p.m. = 3 h

Distance that Zoe's younger sister travelled
= 3 x 97
= 291 km

Distance that Zoe travelled by the time her younger sister reached the city
= 291 - 2
= 289 km

Time that Zoe took to travel 289 km = 5 h

Zoe's average speed
= 289 ÷ 5
= 57⁴₅ km/h

Answer(s): 57⁴₅ km/h