Answer :

To find the degree of the polynomial

[tex]$$9x^8 - 18x^7,$$[/tex]

we follow these steps:

1. Identify the degree (exponent) in each term:
- For the term [tex]$9x^8$[/tex], the degree is [tex]$8$[/tex].
- For the term [tex]$-18x^7$[/tex], the degree is [tex]$7$[/tex].

2. The degree of the polynomial is the highest degree among all terms. Since [tex]$8$[/tex] is greater than [tex]$7$[/tex], the degree of the polynomial is [tex]$8$[/tex].

Thus, the degree of the polynomial is

[tex]$$\boxed{8}.$$[/tex]