Ok, so The price for the amount of popcorn in both boxes is the same, what you want to find out is how much does box #2 cost in total. So do you know how to work with volume? You simply multiply all three slides. so 10 x 20 x 24 = 4,800. Now, since your trying to find the base amount of price per popcorn you need to divide 4,800 by $6.24, the cost of box 1 to find the price per popcorn. 6.24/4,800 = 0.0013. Now you need to find the volume of the second box. 12 x 22 x 20 = 5280. Finally, you multiply 5280 times 0.0013 to get 6.86400. C. is your answer when rounded ;) Good Luck!