Answer
degree = 4
Work Step by Step
Write the terms polynomial in standard form (descending degree) to obtain
$15x^4-8x^3+x^2+91.$
The degree of a polynomial is equal to the degree of the term with the highest degree.
The degree of a term with one variable is equal to the exponent of the variable.
Thus, the terms of the given polynomial have the following degrees:
First term: $4$
Second Term: $3$
Third Term: $2$
Fourth Term: $0$ ( the degree of a constant is 0)
The highest degree is 4, therefore the degree of the polynomial is $4$.