Hello, Can someone please explain the parts period balancing algorithm section, the last section highlighted in yellow and how those answered were derived?

PART PERIOD BALANCING ALGORITHM \begin{tabular}{|l|l|l|l|l|l|l|l|l|l|} \hline \multicolumn{1}{|c|}{ NAME: Drawer DD } & \multicolumn{2}{c|}{ Order Cost = } & $1,800 & \multicolumn{1}{l|}{ Holding Cost. = } & $2.50 & & \\ \hline \multicolumn{1}{|c|}{ WEEK } & 19 & 20 & 21 & 22 & 23 & 24 & 25 & 26 & 27 \\ \hline Gross Requirements (G) & 740 & 616 & 740 & 240 & 0 & 500 & 240 & 980 & 0 \\ \hline Scheduled Receipts (S) & 135 & 212 & & 85 & & 270 & & & 28 \\ \hline Net Requirements (R) & 605 & 404 & 740 & 155 & 0 & 230 & 240 & 980 & 0 \\ \hline \multicolumn{1}{|c|}{ Planned Receipts (P) } & 1009 & 0 & 1125 & 0 & 0 & 0 & 240 & 980 & 0 \\ \hline Holding Cost & $0 & $1,010 & $3,700 & & & & & & \\ \hline Total Cost & $2,810 & & & & & & & & \\ \hline Holding Cost & & & $0 & $388 & $0 & $1,725 & $2,400 & & \\ \hline Total Cost & & & & & & & & \\ \hline Holding Cost & & & & & & & & \\ \hline Total Cost & & & & & & & & \\ \hline Holding Cost & & & & & & & & \\ \hline Total Cost & & & & & & & & \\ \hline \end{tabular} PART PERIOD BALANCING ALGORITHM \begin{tabular}{|l|l|l|l|l|l|l|l|l|l|} \hline \multicolumn{1}{|c|}{ NAME: Drawer DD } & \multicolumn{2}{c|}{ Order Cost = } & $1,800 & \multicolumn{1}{l|}{ Holding Cost. = } & $2.50 & & \\ \hline \multicolumn{1}{|c|}{ WEEK } & 19 & 20 & 21 & 22 & 23 & 24 & 25 & 26 & 27 \\ \hline Gross Requirements (G) & 740 & 616 & 740 & 240 & 0 & 500 & 240 & 980 & 0 \\ \hline Scheduled Receipts (S) & 135 & 212 & & 85 & & 270 & & & 28 \\ \hline Net Requirements (R) & 605 & 404 & 740 & 155 & 0 & 230 & 240 & 980 & 0 \\ \hline \multicolumn{1}{|c|}{ Planned Receipts (P) } & 1009 & 0 & 1125 & 0 & 0 & 0 & 240 & 980 & 0 \\ \hline Holding Cost & $0 & $1,010 & $3,700 & & & & & & \\ \hline Total Cost & $2,810 & & & & & & & & \\ \hline Holding Cost & & & $0 & $388 & $0 & $1,725 & $2,400 & & \\ \hline Total Cost & & & & & & & & \\ \hline Holding Cost & & & & & & & & \\ \hline Total Cost & & & & & & & & \\ \hline Holding Cost & & & & & & & & \\ \hline Total Cost & & & & & & & & \\ \hline \end{tabular}