Students learn to solve equations with the distributive property. For example, to solve 39 = -2(a + 3) – 7a, first distribute through the parentheses, to get 39 = -2a – 6 – 7a. Next, combine like terms, to get 39 = -9a – 6. Next, add 6 to both sides of the equation, to get 45 = -9a. Finally, divide both sides of the equation by –9, to get –5 = a. Note that students check all solutions by substituting the solution back in for the variable or variables in the original equation.