The best layout for your data within a spreadsheet is as a single big rectangle with rows corresponding to subjects and columns corresponding to variables. The first row should contain variable names, and please do not use more than one row for the variable names.
To find out how many $2.50 pencil cases you can buy with $100, you need to divide. Dividing the amount of money you have by the cost of the item will get you the amount of items you can buy. 100 divided by 2.50 is 40. So, you can get 40 cases.
