Marginal and absorption cost

Dear Mr Moffat. I have got below question from Exam kit and it looks like not being correct to me. Question: A new company has set up a marginal costing system and has a budgeted contribution for the period of $ 26,000 based on sale of 13,000 units and production of 15,000 units. This level of production represents the firm's expected long term level of production. The company' s budgeted fixed production cost are $ 3,000 for the period. If the company were to change to an absorption costing system the budgeted profit would be: My working: Absorption rate 3,000/15,000 = $ 0,2 Budgeted contribution $ 26,000 + Closing inventory 2000 (15000-13000)*0.2 $ 400 Profit under absorption costing $26,400 For my knowledge budgeted contribution is equal selling price - total variable cost. Answer gives in the book. Absorption rate 3,000/15,000 = $ 0,2 Budgeted profit with marginal costing: Contribution - fixed cost = $26,000 - $3,000 =$23,000 + Closing inventory 2000 (15000-13000)*0.2 $ 400 Total $23,400. Why do we need to subtract the fixed cost from budgeted contribution if contribution does not include fixed cost? If the answer provided in the book is correct, then I believe I have made some confusion with budgeted contribution. In case could you kindly help me to better understand. Thank you very much for your help. Gabbi