$21)$ Assuming no other use of their facilities, at what buying price per unit for Delta would Delta's operating income be the same whether they made the part or bought it from Vendor?Beta makes a component used in its engine. Monthly production costs for $1,000$ component units are as follows:Direct materials$$46,000$Direct labor$11,500$Variable overhead costs$34,500$Fixed overhead costs$23,000$Total costs$$115\mathrm{.}000$