First we get rid of the parentheses, then we combine the like terms, such as 7n^7 and - 5n^7, and preform the operations (add/substract their coefficients), for example, 7n^7 - 5n^7 = n^7(7 - 5) = 2n^7 .

You can obtain an explanation for any step by clicking on it. Please note that you cannot click on the very first expression, which is the original problem. Quite often, several transformations will be performed within the same step.