<PRE><B>Question 629361</B>
L = Length

W = Width = L-20                   (given)

P = Perimeter = 2*L + 2*W          (definition of perimeter)

P = 2*L + 2*(L-20)                 (substitution)

P = 1200 feet                      (given)

2*L + 2*(L-20) = 1200              (transitive property of equality)

2*L + 2*L - 2*20 = 1200            (distribution)

4*L - 2*20 = 1200                  (addition of like terms)

4*L - 40 = 1200                    (multiplication)

4*L = 1240                         (add 40 to both sides)

L = 1240/4                         (divide both sides by 4)

L = 310                            (simplify)

W = L - 20 = 310 - 20              (substitution) 

W = 290                            (subtraction)

Happy Trails

        

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