Answer:
\(0.03x+2700\)
Step-by-step explanation:
We are asked to find the combined yearly interest for both amounts.
The interest for x dollars invested at 12% would be 12% of x.
\(12\%\text{ of }x=\frac{12}{100}\cdot x=0.12x\)
The interest for \(30,000-x\) dollars at 9% would be 9% of \(30,000-x\).
\(\frac{9}{100}(30,000-x)\)
\(0.09(30,000-x)\)
\(2700-0.09x\)
Combined interest:
\(2700-0.09x+0.12x\)
\(2700+0.03x\)
\(0.03x+2700\)
Therefore, the combined tax would be \(0.03x+2700\).
