Tina took 7/3 hours to travel 4/9 of the distance between town A and town B at an average speed of 72km/hour. what was Tina's average speed if she took 4 hours 12 minutes to travel from town A to town B. 

let the total distance be x

tina took 7/3 hours to travel 4/9x distance at speed of 72 km/hr

so 

distance = speed x time

4/9x = 7/3×72

x= 378 km

now new time is 4 hrs + 12 mins

4 + 12/60 hours

time = 21/5 hours

speed = distance/time

=378×5/21

=90 km/hr