Problem number 13. In an ice cream shop, there was some money in a drawer. After selling 6 ice cream cones, there are $70 in the drawer. After selling a total of 16 ice cream cones, there are $120 in the drawer. How many dollars are there in the drawer at the start? A-20, B-30, C-40, D-50, or E-60. To solve a problem like this, I find it helpful to draw a diagram. There's a certain amount of money that's in the drawer at the beginning. When the store sells 6 ice cream cones, there's now a total of $70. When the store sells 16 ice cream cones, there's now a total of $120. This bar represents 6 ice cream cones, and this bar represents 16 ice cream cones. The difference between 6 ice cream cones and 16 ice cream cones is 16 minus 6, or 10. We can also find the price of the 10 ice cream cones. The 6 ice cream cones and the money that was in the drawer at the beginning is $70, and the 16 ice cream cones and the money that was in the drawer at the beginning is $120. The difference between $120 and $70 will be the price of 10 ice cream cones. 120 minus 70 is 50. 10 ice cream cones cost $50. One ice cream cone costs $50 divided by 10, or $5. Now we can take either one of these numbers, 70 or 120, and find out how much of that money came from selling ice cream cones. I'll go with the smaller number, which might make it a little easier. $70 and 6 times 5, or $30, came from selling the ice cream cones. 70 minus 30 is 40, so there were $40 at the beginning. To double check, we should get the same answer when we use the other numbers. 16 ice cream cones would cost $80. $80 came from selling 16 ice cream cones. 120 minus 80 also gives us $40. Here again, it would show that $40 was in the drawer at the beginning. So the answer is C. There were $40 in the drawer at the start.

ice cream shop

initial amount

cone price

sales calculation

drawer balance