Answer:
200,000 units of Z and 0 of A.
Step-by-step explanation:
For each hour:
8 units of A, at $12: So a gain of 8*12 = $96.
10 units of Z, at $10: So a gain of 10*10 = $100.
Since Z is more profitable, if it is possible to sell only the unit Z, you should do this.
So you have 20,000 production hours avaiable, and at each hour you can produce 10 units of Z. So in all, the most productive sales mix is 200,000 units of Z and 0 of A.