Hi!
The compound interest formula is:
Final amount (A)= Original Amount x
![(1 + (Rate)/(100))^(time)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/aafcgak9xvunr5nl3ehiidez4mro38488e.png)
The rate is the amount of interest.
In this question, your rate is decreasing so it is
![100 - 23 = 77](https://img.qammunity.org/2019/formulas/mathematics/middle-school/vms2wwglw4vicwol3w7p9erp176lh6q7dl.png)
When measuring depreciation, the formula for compound interest changes to:
Original Amount x
![(1 - (Rate)/(100))^(time)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/qw393gzfkdumyrn9tzwupsfnizc665lpqq.png)
This would mean that the answer to one year would be figured out by the following equation:
15000 x
![(1 - (23)/(100) )^1](https://img.qammunity.org/2019/formulas/mathematics/middle-school/pk8k17uc2zbz9jv60q0fz1xvh4kjd2mziu.png)
, this would bring the result out to be $11550
(the time is one as there is only one year for part A).
As for part B, the time is changed to three years so the
![^(time)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/lck2l877201i9m5v1gca4u4yvjqfunwc9l.png)
factor is changed to three, making the formula the following:
15000 x
![(1 - (23)/(100) )^3](https://img.qammunity.org/2019/formulas/mathematics/middle-school/szwvxa3d0lcj7lu3rtsjril3rddd0ubcn5.png)
which would make the answer $6848.
Hope this helped!