We want to calculate the following expression
We will begin by eliminating the parentheses from the expression. To do so we need to distribute the negative sign of the right most parentheses. If we do so we obtain the following equivalent expression
Now, we will group each coefficient separately. That is, we will group terms that have the same coefficient. If we do so, we obtain
Now, if we operate inside each parentheses, we obtain the final expression, which is
