Abi left home at 11.30 a.m. and drove towards the town. 3 hours later, her younger brother left their home and drove towards the same town at 98 km/h. When the younger brother reached the town at 7.30 p.m., Abi had another 4 km to travel. What was Abi’s average speed? Express your answer in mixed number.
Time that the Abi's younger brother started driving = 2.30 p.m.
Duration that Abi's younger brother drove from 2.30 p.m. to 7.30 p.m. = 5 h

Distance that Abi's younger brother travelled
= 5 x 98
= 490 km

Distance that Abi travelled by the time her younger brother reached the city
= 490 - 4
= 486 km

Time that Abi took to travel 486 km = 8 h

Abi's average speed
= 486 ÷ 8
= 60³₄ km/h

Answer(s): 60³₄ km/h