How Do You Subtract a Percentage From a Sum in Excel?
You can use several techniques to subtract a percentage from a sum in Excel. The Houston Chronicle elaborates on a simple method that can be used in versions of the software up to MS Excel 2013.

Calculate the sum
The first step is to calculate the sum with the formula “=sum(cellX:cellY)” entered below the cell range of a sum. For example, the sum for cells A1 to A10 is calculated with the formula “=sum(A1:A10)” inserted into the cell A11.

Enter percentage to be deducted
The percentage to be deducted from the sum should be entered into the adjacent cell of the sum. In this example case, cell B11.

Enter final calculation formula
The formula “=cell of the sum(cell of the sum * cell of the percentage followed by %)” is used to calculate the final result. In the example above, formula “=A11(A11*B11%)” would deduct a percentage set in the cell B11 from the sum of the cell range A1 through A10.