Shiyun left home at 11.20 a.m. and drove towards the suburb. 2 hours later, her cousin left their home and drove towards the same suburb at 89 km/h. When the cousin reached the suburb at 4.20 p.m., Shiyun had another 3 km to travel. What was Shiyun’s average speed? Express your answer in mixed number.
Time that the Shiyun's cousin started driving = 1.20 p.m.
Duration that Shiyun's cousin drove from 1.20 p.m. to 4.20 p.m. = 3 h

Distance that Shiyun's cousin travelled
= 3 x 89
= 267 km

Distance that Shiyun travelled by the time her cousin reached the city
= 267 - 3
= 264 km

Time that Shiyun took to travel 264 km = 5 h

Shiyun's average speed
= 264 ÷ 5
= 52⁴₅ km/h

Answer(s): 52⁴₅ km/h