Explain what is the margin of safety and how is it calculated? Determine how much is his margin of safety expressed in sales revenue and in the number of units for the company below?

ABC Company is owned and operated by a craftsman who makes elaborate birdcages. It is currently producing 40 birdcages per month. Cost data are as follows:

Price $720 per unit

Variable cost $470 per unit

Fixed costs $8,000 per month