$\log _{7} 9$

Step 1 ：The problem is asking for the logarithm base 7 of 9. This means we are looking for the exponent to which we need to raise 7 to get 9. Since this is not a simple calculation, we will need to calculate this.

Step 2 ：\(\log_{7} 9 = 1.1291500681071593\)

Step 3 ：Final Answer: \(\boxed{1.1291500681071593}\)