marginal and absorption

A company manufactures and sells a single product. Next year the budgeted total fixed production costs are $480,000, budgeted sales are 24,000 units and budgeted production is 25,000 units. The budgeted profit for next year using absorption costing principles is $57,500.
What is the budgeted profit for next year using marginal costing principles?
sir the inventory is decreasing so marginal profit should be more isnt it?
but on acca exam paper it’s different.
so answer should be 76600

ans
Budgeted fixed production cost per unit = $19.2 (480,000 / 25,000)

Marginal costing profit = $38,300 (57,500 – (25,000 – 24,000) x 19.2)