please expain

The demand for subassembly S is 90 units in week 7 Each unit of Srequires 1 unit of U. Each unit of Urequires 1 unit of Y and 3 units of Z One firm manufacture all items. It takes 2 weeks to make S. 2 weeks to make U. 2 weeks to make Y, and 1 week to make 2 Click the icon to view the product structure and the time-phased product structure Construct a gross material requirements plan (type O if the input box is not used). Week Lead Time Item 2 (weeks) s Gross req Order release 2 1 3 4 5 6 7 11 DE U Gross reg Order release 2 Y 2 Gross req Order release Gross rog Order release Z BE The product structure. The time-phased product structure. Level V W 0 S T TO UU 1 S E x Y Z UL LY 2 V2) W(2) Xo Yo 23) 6 EN Time in weeks