Requirements:

1. Degree of operating leverage=
2. If the sales decrease by 10% in the following year, by what percentage should net operating income change? Fill in the following table to prove your answer.
3. Please provide clear explanation with answers, thank you!
4. 

Anderson. Co. sells timer priced at $30, variable cost $18, fixed costs total $180 000 a year. Operating results are as follows: Sales $600 000 Variable costs 360 000 Contribution margin 240 000 Fixed costs 180 000 Net operating income $60 000 Requirements: Degree of operating leverage= If the sales decrease by 10% in the following year, by what percentage should net operating income change? Fill in the following table to prove your answer. Current year Following year Sales $600 000 Variable costs 360 000 Contribution margin 240 000 Fixed costs 180 000 Net operating income $60 000