Exercise 25 Page 443

To solve the equation, we have to isolate a on one side. Using the Addition Property of Equality, we can add 3.5 to both sides of the equation. This will eliminate subtraction on the left-hand side and isolate a.

To check that this solution is correct, let's substitute a=18.4 into the original equation and simplify.

Because the left-hand side and right-hand side are equal, a=18.4 is the correct solution.