model answer is shown in the picture. could you please explain why the mps receipt and mps start are $100,150,$ and $130?$

here is the question:

A company produces an end item Alpha. One unit of item Alpha can be made by assembling $1$ unit of X$,2$ units of Y$,$ and $3$ units of Z$.$ Each X is made of $2$ units of Z and $2$ units of A; each Y is assembled using $3$ units of B and $1$ unit of C; each Z is made of $1$ unit of D$.$ On$-$hand inventories are $90$ units of X and $150$ units of Z$.$ Scheduled receipts are $50$ units of X at the beginning of week $1,200$ units of Z at the beginning of week $2,$ and $50$ units of C at the beginning of week $1.$ Lead times for X and C are one week, and lead times for other components are two weeks. Final assembly of Alha requires one week$\mathrm{.}1.$ Fill in Table $1$ to prepare a master production schedule for end item Alphausing the xed period of $2$ rule. The beginning inventory for Alphais $160$; the forecast and promised customer orders for Alpha are provided in this table. $[4$ marks$]$