Answer:
The length is 15 yards
Step-by-step explanation:
Given
Represent the width with W and length with L: So


Required
Determine the length of the rectangle:
Area is calculated as thus:

Substitute 3W - 12 for L and 135 for Area


Reorder:

Divide through by 3

Expand:



or 
or 
But width can't be negative
So:

Recall that: 


<em>Hence, the length 15 yards</em>