mos and bep related

a company produces and sells a single product. Budgeted sales are $2.4m, budgeted fixed costs are $360,000 and the margin of safety is $400,000. What are the budgeted variable costs? answer is $1.968m bep = 2.4m - 400k = 2m c/s = 360k/2m = 18% variable cost = 82% budgeted variable cost = 2400*82% i understand how to do most of the calculation, but the final calculation of 2400*82% is what i dont understand, why isnt it (2400-360)*82%? arent we suppose to find the variable cost from the total costs?