The award was given to the best play, musical or non-musical, which had already appeared on Broadway in a previous production.
No award was presented in 1979.
... to the left of "=", that will make it a perfect square trinomial of the form x2 + 2xy + y2. Since "2xy" in this case is (b/a)x, we must have y = b/(2a), so we add the ...