Verified Answer :

Sum:

     3x^5y - 2x^3y^4 - 7xy^3
 + -8x^5
y + 2x^3y^4 +xy^3
---------------------------------------
     -5x^5y - 6xy^3

Term 1: Degree = 6
Term 2: Degree = 4

Difference:

     3x^5y - 2x^3y^4 - 7xy^3
 -  -8x^5
y + 2x^3y^4 +xy^3
---------------------------------------
     11x^5y - 4x^3*y^4 - 8xy^3

Term 1: Degree = 6
Term 2: Degree = 7
Term 3: Degree = 4

The degree of a term of a polynomial can be obtained by adding the exponents of the variables in that term.