Irene left home at 11.15 a.m. and drove towards the town. 2 hours later, her cousin left their home and drove towards the same town at 79 km/h. When the cousin reached the town at 6.15 p.m., Irene had another 3 km to travel. What was Irene’s average speed? Express your answer in mixed number.
Time that the Irene's cousin started driving = 1.15 p.m.
Duration that Irene's cousin drove from 1.15 p.m. to 6.15 p.m. = 5 h

Distance that Irene's cousin travelled
= 5 x 79
= 395 km

Distance that Irene travelled by the time her cousin reached the city
= 395 - 3
= 392 km

Time that Irene took to travel 392 km = 7 h

Irene's average speed
= 392 ÷ 7
= 56 km/h

Answer(s): 56 km/h