Xylia left home at 11.15 a.m. and drove towards the seaside resort. 2 hours later, her cousin left their home and drove towards the same seaside resort at 86 km/h. When the cousin reached the seaside resort at 5.15 p.m., Xylia had another 2 km to travel. What was Xylia’s average speed? Express your answer in mixed number.
Time that the Xylia's cousin started driving = 1.15 p.m.
Duration that Xylia's cousin drove from 1.15 p.m. to 5.15 p.m. = 4 h

Distance that Xylia's cousin travelled
= 4 x 86
= 344 km

Distance that Xylia travelled by the time her cousin reached the city
= 344 - 2
= 342 km

Time that Xylia took to travel 342 km = 6 h

Xylia's average speed
= 342 ÷ 6
= 57 km/h

Answer(s): 57 km/h