If two opposite sides of a square are increased by 9 meters

If two opposite sides of a square are increased by 9 meters and the other sides are decreased by 7 meters, the area of the rectangle that is formed is 80 square meters. Find the area of the original square

let x = the side of the original square
area of new rectangle is:
(x + 9)(x - 7) = 80
solve for x:
x^2 + 2x - 63 = 80
x^2 + 2x -143 = 0
(x +13)(x - 11) = 0
x = 11

x=-13 as the result is negative , it is not the solution we seek