I have a rectangle which consists of a width of 10", and a length of 40". THis gives me a total area of 400" (w x l= a). If I reduce the area by a percentage, lets say 10% my reduced area is now 360" (400 - 40 = 360.) What is the formula to determine the reduced size of the width and the length.

W = 10"

L = 40"

A = 400

reduced rectangle 10% of area

A2 = 360

W2 = ?

L2 = ?

Thanks for your help.