Given:Side of the square plot = 84 mNow, the man wants to exchange it with a rectangular plot of the same area with length 144.  Area of the square plot = 84×84 = 7056 m2 ∴ Area of the rectangular plot = Length x Width7056 = 144 x Width ⇒ Width =1447056​=49 mHence, the width of the rectangular plot is 49 m.