No that statement is not always true. There is only one solution to this equation.
Answer:
3x^2 + 3xy/2 - 7xy^2/2
Step-by-step explanation:
So we know the perimeter is 20x^2 + xy - 7y^2,
To find any perimeter you need 2l + 2w = P so,
One of the sides is 7x^2 - xy
First plug in the values,
2(7x^2-xy) + 2w = 20x^2 + xy - 7y^2
Multiply,
14x^2-2xy + 2w = 20x^2 + xy - 7y^2
Subtract,
14x^2 - 2xy - 14x^2 + 2xy + 2w = 20x^2 + xy - 7y^2 - 14x^2 + 2xy
2w = 6x^2 + 3xy - 7y^2
w = 3x^2 + 3xy/2 - 7xy^2/2
The measurement of PON is about 180 degrees
Hello!
The answer to your problem is: 
<u>Simplify both sides of the equation</u>


<u>Subtract 2/3x from both sides</u>


<u>Subtract 2 from both sides</u>


<u>Multiply both sides by 3/(-26)</u>

<u>Get your answer</u>

Hope This Helps!