Tammy left home at 11.10 a.m. and drove towards the countryside. 2 hours later, her grandmother left their home and drove towards the same countryside at 93 km/h. When the grandmother reached the countryside at 4.10 p.m., Tammy had another 5 km to travel. What was Tammy’s average speed? Express your answer in mixed number.
Time that the Tammy's grandmother started driving = 1.10 p.m.
Duration that Tammy's grandmother drove from 1.10 p.m. to 4.10 p.m. = 3 h

Distance that Tammy's grandmother travelled
= 3 x 93
= 279 km

Distance that Tammy travelled by the time her grandmother reached the city
= 279 - 5
= 274 km

Time that Tammy took to travel 274 km = 5 h

Tammy's average speed
= 274 ÷ 5
= 54⁴₅ km/h

Answer(s): 54⁴₅ km/h