Xuan left home at 11.40 a.m. and drove towards the countryside. 2 hours later, her grandfather left their home and drove towards the same countryside at 95 km/h. When the grandfather reached the countryside at 4.40 p.m., Xuan had another 6 km to travel. What was Xuan’s average speed? Express your answer in mixed number.
Time that the Xuan's grandfather started driving = 1.40 p.m.
Duration that Xuan's grandfather drove from 1.40 p.m. to 4.40 p.m. = 3 h

Distance that Xuan's grandfather travelled
= 3 x 95
= 285 km

Distance that Xuan travelled by the time her grandfather reached the city
= 285 - 6
= 279 km

Time that Xuan took to travel 279 km = 5 h

Xuan's average speed
= 279 ÷ 5
= 55⁴₅ km/h

Answer(s): 55⁴₅ km/h