How do you subtract two numbers?
Subtraction is an operation that identifies the total count of objects in a collection of items after a specific count of items are removed from the starting total.

You can subtract two numbers by starting with an initial count, which represents the number to subtract from, and a second count which represents the number to subtract.  Then remove one from the starting count repeating this operation for the number of items in the subtract value.  

Subtraction is not associative, which means that the order in which subtraction is performed matters.  For instance, seven minus five (7 - 3) equals four (= 4) but four minus seven (4 - 7) equals minus three (= -3).