How do I go about in getting the formula for excel. The instructions are on the picture.

Classroom Supplies Cost/Unit Sept. Units Sept. Cost % of Grand Total Oct. Units Oct. Cost % of Grand Total Copy Paper $3.99 #2 Pencils $0. 75 Pens $4.00 co Highlighters $3.29 Markers $4.79 10 Crayons $3.10 11 Colored Pencils $2.29 12 Staples $1.89 13 Tissues $1.49 14 Hand Sanitizer $2.00 JANNEY8 AN9 15 Figure 2 7. In column D, enter appropriate formulas to calculate the September costs for each school supply. Your formulas must use cell references. Format the calculated values as Currency with 2 decimal places. 8. In cell A16, enter the label "Grand Total" and then format it as bold. 9. In cell D16, enter a formula that uses a function to calculate the total of the column