Solution and Explanation:
The following is the incremental analysis for the make - or the buy decision to be made by the Parks corporation based on the data given in the question
Incremental cost to buy -54000 = 3000 multiply with 18
Incremental savings on direct materials 9000 =3000 multiply with 3
Incremental savings on direct labor 21000 =3000 multiply with7
Incremental savings on variable overhead 12000 =3000 multiply with4
Incremental savings on fixed overhead 6000 =3000 multiply with2
Incremental net cost to buy -6000