For this exercise it is important to remember the following:
1. The parentheses can be used in mathematical expresssions to group terms.
2. An equation is defined as a statement in which two algebraic expressions are separated by this sign:
Then, the expression on the left of that sign and the expression on the right have the same value.
In this case, you have the following equation given in the exercise:
To make this equation true, the left side must be equal to the right side. In other words, both sides must be 9.
In order to do that, you need to use parentheses to make the correct groups.
Based on the above, you get:
Therefore, the answer is:
