Consider the question. Ronald can grill 15 hamburgers per session on his new grill. He needs to cook 115 hamburgers in total for tonight's party. He has already cooked 40 hamburgers. How many more sessions will it take Ronald to finish cooking all 115 hamburgers?
 If the answer is '5'; explain the reasoning:
He has to cook 115 hamburgers and has already cooked 40 so he needs to cook 115 - 40 = 75 more hamburgers. He can only cook 15 hamburgers at a time so that means he has to cook 75 / 15 = 5 more cooking sessions.