In this case, we'll have to carry out several steps to find the solution. 
Step 01:
Data
2x^5+7x^4-x^3 
degree = ? 
Step 02:
2x^5 ===> degree = 5 
The degree of the polynomial is the highest exponent.
It is a polynomial of fifth degree. 
The answer is: 
It is a polynomial of fifth degree.