For this case we have the following polynomials:

By subtracting both polynomials we have:

What we must do is subtract terms of the same degree.
We have then:
Answer:
will be a polynomial
Answer:
6
Step-by-step explanation:
= - 
given
= 5 ( cross- multiply )
5(x + y) = x - y
5x + 5y = x - y ( subtract (x - y) from both sides )
4x + 6y = 0 ( subtract 6y from both sides )
4x = - 6y
= -
= - 
The answer is the additive identity postulate.