Esther left home at 11.15 a.m. and drove towards the town. 2 hours later, her father left their home and drove towards the same town at 99 km/h. When the father reached the town at 5.15 p.m., Esther had another 3 km to travel. What was Esther’s average speed? Express your answer in mixed number.
Time that the Esther's father started driving = 1.15 p.m.
Duration that Esther's father drove from 1.15 p.m. to 5.15 p.m. = 4 h

Distance that Esther's father travelled
= 4 x 99
= 396 km

Distance that Esther travelled by the time her father reached the city
= 396 - 3
= 393 km

Time that Esther took to travel 393 km = 6 h

Esther's average speed
= 393 ÷ 6
= 65¹₂ km/h

Answer(s): 65¹₂ km/h