I've done hundreds of these.

w = width

w + 9 = length {length is 9 more than the width}

Perimeter of a rectangle = 2(width) + 2(length}

2w + 2(w + 9) = 138 {substituted width and length into perimeter formula}

2w + 2w + 18 = 138 {used distributive property}

4w + 18 = 138 {combined like terms}

4w = 120 {subtracted 18 from each side}

w = 30 {divided each side by 4}

**width is 30 yards**length = w + 9

= 30 + 9 {substituted 30, in for w, into w + 9}

= 39 {added}

**length is 39 yards***- Algebra House*
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