Question 29329
average speed = total distance/time taken


First, the initial part:
80 = distance/2
--> distance = 160km.


So, for average speed of 75, we have travelled 160+x, where x is the distance we are asked for. Total time is 3 hours. So,


(160+x)/3 = 75
160+x = 225
x = 65km.


jon.