Ali & Co. produces 20,000 units of part 'X' every month and used it in assembling a product. Its cost structure is as follows: Variable cost OMR 10 Fixed cost OMR 5 Total cost OMR 15 It is proposed to obtain the part from open market at OMR 12 per unit. You are required to advise the management on the above proposal and help in arriving at the correct decision whether to make or buy.