The equation is .

               (Subtract 20h from each side)

The perfect square of the given trinomial .

                     (Take the square root of each side)

Apply square roots property: If then .

Apply addition property of equality: If a = b then .

                             (Add 5 to each side)

                 (Apply additive inverse property: )

                              (Divide each side by 2)

The solution is .