Can anyone please help me understand this? Thanks

A company with a break-even point at $900,000 in sales revenue had fixed costs of $225,000. When actual sales were $1,000,000 variable costs were $750,000. Determine the following. Round the contribution margin ratio to one decimal place. a. Margin of safety expressed in dollars b. Margin of safety expressed as a percentage of sales c. Contribution margin ratio d. Operating income