quadratic equations and area of rectangle

Question

The area of a rectangular wall in a classroom is 280 square feet. Its length is 2 feet shorter than three times its width. Find the width of the wall of the classroom.

Answer 1

Area = 280 sq f

L = 3W - 2

3W - L = 2 -----> 1

Area = 280

2 ( L + W) = 280

L + W = 140 ----> 2

solving equations 1 and 2

L + W = 140

-L + 3W = 2

--------------------

4W = 142

W = 35.5

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