Question $4.$ The demand for subassembly $S$ is $100$ units in week $7.$ Each unit of $S$ requires $1$ unit of $T$ and $2$ units of $U.$ Each unit of $T$ requires $1$ unit of $V,2$ units of $W,$ and $1$ unit of $x.$ Finally, each unit of $U$ requires $2$ units of $Y$ and $3$ units of Z$.$ One firm manufactures all items. It takes $2$ weeks to make S$,1$ week to make T$,2$ weeks to make U$,2$ weeks to make V$,3$ weeks to make $W,1$ week to make $x,2$ weeks to make $Y,$ and $1$ week to make $Z.$

a$)$ Construct a product structure. Identify all levels, parents, and components.

b$)$ Prepare a time$-$phased product structure.

c$)$ Construct a net material requirements plan using the following on$-$hand inventory.

$\backslash$table$[[$ITEM$,\backslash$table$[[$ON$-$HAND$],[$INVENTORY$]],$ITEM,$\backslash$table$[[$ON$-$HAND$],[$INVENTORY$]]],[$S$,20,$W$,30],[$T$,20,$X$,25],[U,40,Y,240],[$V$,30,Z,40PP$