Incorrect. Remember that each term within the parentheses must be multiplied by the expression on the outside of the parentheses. You can think of the expression as $\displaystyle{\left({5}{x}\cdot{12}{a}\right)}+{\left({5}{x}\cdot-{b}\right)}+{\left({5}{x}\cdot-{3}{c}\right)}\usepackage{cmbright}\Huge\$ .