Vanessa left home at 11.30 a.m. and drove towards the province. 3 hours later, her grandmother left their home and drove towards the same province at 100 km/h. When the grandmother reached the province at 7.30 p.m., Vanessa had another 6 km to travel. What was Vanessa’s average speed? Express your answer in mixed number.
Time that the Vanessa's grandmother started driving = 2.30 p.m.
Duration that Vanessa's grandmother drove from 2.30 p.m. to 7.30 p.m. = 5 h

Distance that Vanessa's grandmother travelled
= 5 x 100
= 500 km

Distance that Vanessa travelled by the time her grandmother reached the city
= 500 - 6
= 494 km

Time that Vanessa took to travel 494 km = 8 h

Vanessa's average speed
= 494 ÷ 8
= 61³₄ km/h

Answer(s): 61³₄ km/h