What is meant by the term relevant range?

Include the following in your post: Explain variable costs, fixed costs, and mixed costs. What is meant by the term relevant range? What is contribution margin and how is it calculated? Explain the three methods: the equation approach, the contribution approach, and the contribution margin approach to calculate the break-even point. Present a chart that depicts the four steps that are necessary to develop the CVP chart. What is margin of safety and operating leverage?