The demand for subassembly S is $110$ units in week $7.$ Each unit of S requires $2$ units of T and $2$ units of U$.$ Each unit of T requires $1$ unit of$$ V$,1$ unit of$$ W$,$ and $2$ units 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$$ U$,1$ week to make$$ V$,3$ weeks to make$$ WIn addition to $110$ units of$$ S$,$ there is also a demand for $20$ units of$$ U$,$ which is a component of S$.$ The $20$ units of U are needed for maintenance purposes. These units are needed in week $6.$ Modify the gross material requirements plan to reflect this change, $2$ weeks to make$$ X$,2$ weeks to make$$ Y$,$ and $2$ weeks to make Z$.$