Barbara left home at 11.45 a.m. and drove towards the seaside resort. 3 hours later, her younger brother left their home and drove towards the same seaside resort at 93 km/h. When the younger brother reached the seaside resort at 7.45 p.m., Barbara had another 3 km to travel. What was Barbara’s average speed? Express your answer in mixed number.
Time that the Barbara's younger brother started driving = 2.45 p.m.
Duration that Barbara's younger brother drove from 2.45 p.m. to 7.45 p.m. = 5 h

Distance that Barbara's younger brother travelled
= 5 x 93
= 465 km

Distance that Barbara travelled by the time her younger brother reached the city
= 465 - 3
= 462 km

Time that Barbara took to travel 462 km = 8 h

Barbara's average speed
= 462 ÷ 8
= 57³₄ km/h

Answer(s): 57³₄ km/h