What is the degree of the expression $-8 x^{4} y^{5}+9 y^{7}-3 x y^{4}-6 x-2$ ? 5 $-8$ 7 9

Step 1 ：The degree of a polynomial is the highest power of the variable in the polynomial. In this case, we need to find the highest power of the variable in the given expression. The expression is \(-8 x^{4} y^{5}+9 y^{7}-3 x y^{4}-6 x-2\).

Step 2 ：The powers of the variables in the terms are 4+5=9, 7, 1+4=5, 1, and 0 respectively.

Step 3 ：So, the highest power is 9. Therefore, the degree of the expression is 9.

Step 4 ：Final Answer: The degree of the expression \(-8 x^{4} y^{5}+9 y^{7}-3 x y^{4}-6 x-2\) is \(\boxed{9}\).