Attached image is the detail answer to your question.
<span>How much more will it cost Olivia if she uses the credit card instead of the personal loan?
it will cost 2,880</span>
we have the function

Remember that
The Amplitude is the height from the center line to the peak (or to the trough). Or we can measure the height from highest to lowest points and divide that by 2
In the general form of the equation of the sine

The amplitude is the factor A
so
In this problem
The amplitude is 1/2
using a graphing tool
Note that the amplitude is the height from the center line to the peak (the center line is the x-axis, so the distance is 0.5.
Finding the perimetre: 7x+4x-3+x=12x-3
Good luck!