The equation is .

    (Add 9 to each side) \ \

                   (Square each side and eliminate the square roots)

                      (Evaluate power: ) \ \

                  (Multiply) \ \

                   (Divide each side by 4) \ \

\ \

Check:

To check the solution, substitute in .

                        (Evaluate square roots: )

The solution is "True".

The solution is 180.