Diana left home at 11.45 a.m. and drove towards the city. 3 hours later, her grandmother left their home and drove towards the same city at 95 km/h. When the grandmother reached the city at 7.45 p.m., Diana had another 3 km to travel. What was Diana’s average speed? Express your answer in mixed number.
Time that the Diana's grandmother started driving = 2.45 p.m.
Duration that Diana's grandmother drove from 2.45 p.m. to 7.45 p.m. = 5 h

Distance that Diana's grandmother travelled
= 5 x 95
= 475 km

Distance that Diana travelled by the time her grandmother reached the city
= 475 - 3
= 472 km

Time that Diana took to travel 472 km = 8 h

Diana's average speed
= 472 ÷ 8
= 59 km/h

Answer(s): 59 km/h