Given:
The original price of the computer, CP = $900.
The discount rat offered on all computers, R=10%
Kalesha has a $100 gift card.
The discount is applied on the original price of the computer. So, Kalesha should first take 10% off and then only subtract $100 from it.
Therefore, the answer is " Take 10% off, then subtract $100.
The discount amount for the computer is calculated as,
![\begin{gathered} D=(R)/(100)* CP \\ =(10)/(100)*900 \\ =90 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/ub4f3lkd4mam2p73rfw3d29dzsnbmfxi50.png)
Now, the amount after taking 10% off is,
![\begin{gathered} A=CP-D \\ =900-90 \\ =810 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/high-school/7uizhcntyprlm1z7tjf0o6b6zrxaa0oo2d.png)
There is a $100gift card. So, the final amount that Kalesha should pay can be calculated as,
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