An order release for $200$ X$\text{'}$s is planned for period $6.$ Y$\text{'}$s and Z$\text{'}$s are used to make X$\text{'}$s$.$ To make an X$,$ it takes $2$ Y$\text{'}$s and $4$ Z$\text{'}$s$.$ How many Z$\text{'}$s will appear in the MPS for period $6,$ because of the order release for $200$ X$\text{'}$s$?$