Xylia left home at 11.10 a.m. and drove towards the city. 2 hours later, her father left their home and drove towards the same city at 87 km/h. When the father reached the city at 4.10 p.m., Xylia had another 3 km to travel. What was Xylia’s average speed? Express your answer in mixed number.
Time that the Xylia's father started driving = 1.10 p.m.
Duration that Xylia's father drove from 1.10 p.m. to 4.10 p.m. = 3 h

Distance that Xylia's father travelled
= 3 x 87
= 261 km

Distance that Xylia travelled by the time her father reached the city
= 261 - 3
= 258 km

Time that Xylia took to travel 258 km = 5 h

Xylia's average speed
= 258 ÷ 5
= 51³₅ km/h

Answer(s): 51³₅ km/h