Barbara left home at 11.25 a.m. and drove towards the city. 3 hours later, her mother left their home and drove towards the same city at 83 km/h. When the mother reached the city at 7.25 p.m., Barbara had another 5 km to travel. What was Barbara’s average speed? Express your answer in mixed number.
Time that the Barbara's mother started driving = 2.25 p.m.
Duration that Barbara's mother drove from 2.25 p.m. to 7.25 p.m. = 5 h

Distance that Barbara's mother travelled
= 5 x 83
= 415 km

Distance that Barbara travelled by the time her mother reached the city
= 415 - 5
= 410 km

Time that Barbara took to travel 410 km = 8 h

Barbara's average speed
= 410 ÷ 8
= 51¹₄ km/h

Answer(s): 51¹₄ km/h