Answer:
$13400
Step-by-step explanation:
Workings
Unit of of production
Direct materials - 3.10
Direct labor - 7.70
Variable manufacturing overhead - 8.2
Supervisor's salary - 3.6
Depreciation - 2.00
Allocated general overhead 7.20
Total cost - 31.8
Cost per year = 31.8*14000
445,200
Cost of buying = 25.50
Allocated general overhead - 7.20
Total cost =32.7
Annual cost 32.7*14000 = 457800
Annual opportunity cost of internal production = 26,000
The overall advantage of buying = 26000 - (457800-445200)
= 13,400