Opal left home at 10.55 a.m. and drove towards the town. 3 hours later, her older brother left their home and drove towards the same town at 89 km/h. When the older brother reached the town at 6.55 p.m., Opal had another 3 km to travel. What was Opal’s average speed? Express your answer in mixed number.
Time that the Opal's older brother started driving = 1.55 p.m.
Duration that Opal's older brother drove from 1.55 p.m. to 6.55 p.m. = 5 h

Distance that Opal's older brother travelled
= 5 x 89
= 445 km

Distance that Opal travelled by the time her older brother reached the city
= 445 - 3
= 442 km

Time that Opal took to travel 442 km = 8 h

Opal's average speed
= 442 ÷ 8
= 55¹₄ km/h

Answer(s): 55¹₄ km/h