Exercise $5-4($Algo$)$ Computing and Using the CM Ratio $[$LO$5-3]$

Last month when Holiday Creations, Inc., sold $42,000$ units, total sales were $$168,000,$ total variable expenses were $$137,760,$ and fixed expenses were $$36,600.$

Required:

What is the company's contribution margin $($CM$)$ ratio?

What is the estimated change in the company's net operating income if it can increase sales volume by $450$ units? $($Do not round intermediate calculations.$)$