Hayek Bikes prepares the income statement under variable costing for its managerial reports, and it prepares the income statement under absorption costing for external reporting. For its first month of operations, 375 bikes were produced and 225 were sold; this left 150 bikes in ending inventory. The income statement information under variable costing follows.

Sales (225 $1,600)	$	360,000
Variable product cost (225 $625)		140,625
Variable selling and administrative expenses (225 $65)		14,625
Contribution margin		204,750
Fixed overhead cost		56,250
Fixed selling and administrative expense		75,000
Net income	$	73,500

The dollar difference in variable costing income and absorption costing income = ______ units X $______ fixed overhead per unit.