First, you have to multiply 50 boxes of ice cream by 12 bars to get the total number of ice cream bars. 50 x 12 = 600. That's how many bars of ice cream you had to begin with. Then, you take how many people had ice cream bars (520) and subtract it from the amount of bars you had to begin with. 600 - 520 = 80. You had 80 bars of ice cream left.
