Please assist me with this question, I am unsure of the approach

Xebex Pty Ltd is considering whether to make or buy a machine part used in the production of Pa: Machines. The annual costs of producing the 100,000 machine parts used by the company are as follows. Variable manufacturing costs 310 000 Fixed manufacturing costs 100, 000 Allocated overhead 50, 000 Xebex received an offer from Zeek to supply the 100,000 machine parts. If Xebex accepts the offer they will discontinue production of the machine part, and the fixed manufacturing costs would be reduced by 30%. Xebex should buy the 100,000 components if the cost of purchasing per unit is less than what amount