I just wanted to know what formula are used to make these calculations I reallly need the answers

Classroom Supplies Cost/Unit Sept.Units Sept.Cost % of Grand Total Oct.Units Copy Paper $3.99 40 $159.60 21% 32 #2 Pencils $0.75 29 $21.75 3% 12 Pens $4.00 22 $88.00 12% 8 Highlighters $3.29 12 $39.48 5% 10 Markers $4.79 35 $167.65 22% 22 Crayons $3.10 15 $46.50 6% Colored Pencils $2.29 60 $137.40 18% 28 Staples $1.89 12 $22.68 3% Tissues $1.49 22 $32.78 4% Hand Santizer $2.00 16 $32.00 4% Grand Total $747.84 Chart Title $180.00 $160 00