Subtracting numbers is one of the basic operations in math. Firstly, the order of operations is as follows: PEMDAS or parentheses, exponents, multiplication, division, addition, then subtraction.
All of these are done in the exact order given above.
For example, given the equation (4 x 7) + (6 / 2) - 3^2 = ?
1. Parentheses - Solve the equations within the parentheses first. (4 x 7) + (6 / 2) - 3^2 = 28 + 3 - 3^2
2. Exponents - Second, if there are any exponents, solve this. 28 + 3 - 3^2 = 28 + 3 - 9