Barbara left home at 11.45 a.m. and drove towards the town. 2 hours later, her older brother left their home and drove towards the same town at 100 km/h. When the older brother reached the town at 4.45 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 older brother started driving = 1.45 p.m.
Duration that Barbara's older brother drove from 1.45 p.m. to 4.45 p.m. = 3 h

Distance that Barbara's older brother travelled
= 3 x 100
= 300 km

Distance that Barbara travelled by the time her older brother reached the city
= 300 - 5
= 295 km

Time that Barbara took to travel 295 km = 5 h

Barbara's average speed
= 295 ÷ 5
= 59 km/h

Answer(s): 59 km/h