Question 791394
d = rt


d = 72t


87.5 = 72t


87.5/72 = t


t = 87.5/72


t = 1.2152777


So you have spent 1.2152777 hours roughly traveling 87.5 km.


There are 2.5 - 1.2152777 = 1.2847223 hours left and you must travel 87.5 km back to the original starting location


d = rt


87.5 = r*1.2847223


87.5/1.2847223 = r


r = 68.1081039


So the return speed must be roughly <font color="red">68.1081039 km/hr</font>