Answer:
The desired profit from the sale and production of K is 10% of invested amount=10%*$1285000
       =$128500
cost per unit =$18.68
b.total manufacturing cost=$18.68*50000=$934000
cost per unit remains=$18.68
Profit per unit =$2,57
markup %=2.57/18.68=13.76%
Selling price =cost+mark up
            =$18.68+$2.57
            =$21.25
Explanation:
I have attached an excel file for further understanding on the formulas used above,please check out the file in order to gain  better insights into the exercise.