We know that the final price of the couch is $27.23. This includes the 5.5% commission for the salesperson.
Then, we can define X as the price before commission.
The commission of the salesperson becomes 5.5/100*X=0.055X.
Then, the final price can be written as:

This price before commission X=25.81 is what the store get from the sale.
We can calculate the commission as:

If we add the commission to the price before commission, we get:

Answer: $25.81