The sale tax rate is 5.5%
Proof : 8 x 5.5% = $8.44
The "compound amount" formula is A = P(1+r)^t.
Here, the Amount A(x) is (x)(1+0.03)^1= 1.03x.
Please be clearer about what you are asking here. I assume you just wanted to be told that you are right.
When you need to identify elements in an informative manner. It also provides the essential information needed to balance chemical equations.