I have no idea how to get the correct answer of 25.7

Last year, Harris Company manufactured 17,000 units and sold 13,000 units. Production costs for the year were as follows: Direct materials... f153,000 Direct labour......... f110,500 Variable manufacturing overhead. f204,000 Fixed manufacturing overhead... f255,000 Other details for the year are: Sales.. f780,000 Variable selling and administrative expenses... $88,400 Fixed selling and administrative expenses......... f170,000 Beginning inventory......... nil Assume that direct labour is a variable cost. The contribution margin per unit was: Select one: f17.50 x Incorrect. Contribution margin per unit = selling price per unit - variable cost per unit. Selling price per unit = E60. Variable cost per unit = (467,500 / 17,000) + (88,400 / 13,000) = f34.30. f25.70 f32.50 O f27.30 The correct answer is: $25.70