Question

The combined yearly interest for x dollars invested at 12% and 30,000 - x dollars invested at 9% is

Answer 1

.12x + .09(30000-x)=interest earned

Answer 2

`0.03x+2700`

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=(12)/(100)\cdot x=0.12x`

The interest for
`30,000-x` dollars at 9% would be 9% of
`30,000-x`.

`(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`.