Question 603370
A = LW


144 = x(x+7)


x(x+7) = 144


x^2+7x = 144


x^2+7x-144 = 0


(x+16)(x-9) = 0


x+16 = 0 or x-9 = 0


x = -16 or x = 9


Throw out the negative solution to get the only solution of x = 9


So the width is x = <font color="red">9 cm</font> and the length is x+7 = 9+7 = <font color="red">16 cm</font>.