D. I’m not sure but try that
For this case we have the following subtraction:

We can rewrite the subtraction in an easier way.
We have then:

Then, by doing associative property we have:

Answer:
The value of the subtraction is given by:

I’m confused, what’s the questions asking for?
Answer:
first year $20 second year $20.80 Third year $21.63
Step-by-step explanation: This is for an extra money per year so after the first year that is how much extra money he gets every year.