The area of a square garden is Q square feet and the perimeter is P feet. If Q=P+21, what is the perimeter of the garden in feet? Choose the correct choice from the following options:
A) 24  B) 28  C) 32  D) 36  E) 40

Rationale: let x be the length of one side of the square garden . x ^ 2 = 4 x + 21 x ^ 2 - 4 x - 21 = 0 ( x - 7 ) ( x + 3 ) = 0 x = 7 , - 3 p = 4 ( 7 ) = 28 the answer is b .
Answer: B