The first step is the application of the distributive property: the factors outside the parenthesis are written multiplying the terms within the parenthesis.
The second step is grouping similar terms: this allows us to simplify the terms that are function of x and the terms that are not.
The third step is adding/substracting similar terms, like 2x-3x=-x. This let us finish what we started with the second step and have a simplified expression.