Ensure variables and exponents are the same. For instance, you cannot subtract powers in the following equation: 3X-2Y. But you can subtract powers in the following equation, since the variables and exponents are the same: 4X(2)-2X(2).
Subtract the coefficients -- the numbers that precede the variable. For instance, in the equation 4X(2) - 2X(2), the coefficients are 4 and 2. The solution to this part of the equation is thus 4 - 2 = 2.
Subtract the exponents. Since the exponents in our example equation are the same -- both are to the power of 2 -- we can subtract them. So, the equation would be X(2) - X(2)=X.
Solve for the entire equation by subtracting both components. Given what we know about the two components of the equation, we know that 4X(2) - 2X(2) = 2X, since 4 - 2 = 2 -- for the coefficients -- and 2 - 2 = 0 -- for the exponents.