Procedure:
Step 1 – Open LibreOffice calc worksheet Applications → Office → LibreOffice Calc
Step 2 – Enter the following data in the given cells

Step 3 – Enter the given formula in cell E2 = B2 + C2 + D2
Step 4 – Drag the formula to E7 to get the total sales of each salesman
Step 5 – Enter the given formula in cell E8 to get the total sales of the firm = SUM (E2: E7)
Output :
