Dana left home at 10.25 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 83 km/h. When the younger brother reached the seaside resort at 6.25 p.m., Dana had another 5 km to travel. What was Dana’s average speed? Express your answer in mixed number.
Time that the Dana's younger brother started driving = 1.25 p.m.
Duration that Dana's younger brother drove from 1.25 p.m. to 6.25 p.m. = 5 h

Distance that Dana's younger brother travelled
= 5 x 83
= 415 km

Distance that Dana travelled by the time her younger brother reached the city
= 415 - 5
= 410 km

Time that Dana took to travel 410 km = 8 h

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

Answer(s): 51¹₄ km/h