Kimberly left home at 11.15 a.m. and drove towards the seaside resort. 3 hours later, her younger sister left their home and drove towards the same seaside resort at 97 km/h. When the younger sister reached the seaside resort at 7.15 p.m., Kimberly had another 5 km to travel. What was Kimberly’s average speed? Express your answer in mixed number.
Time that the Kimberly's younger sister started driving = 2.15 p.m.
Duration that Kimberly's younger sister drove from 2.15 p.m. to 7.15 p.m. = 5 h

Distance that Kimberly's younger sister travelled
= 5 x 97
= 485 km

Distance that Kimberly travelled by the time her younger sister reached the city
= 485 - 5
= 480 km

Time that Kimberly took to travel 480 km = 8 h

Kimberly's average speed
= 480 ÷ 8
= 60 km/h

Answer(s): 60 km/h