Kaplan Incremental approach to budget pg132

Hi, Trying to figure out how example given on the above page in current Kaplan book ties out if rather than applying 4% increase to cost per unit but applying increase in cost to total variable costs for product C in 2004? Difference in total cost is 203,674 per the book to 209,664 per my calculation. Can you help me out what I'm missing here? 672,000 total cost * .75 = 504,000 504,000 * .40 = 201,600 total variable cost 2004 cost increased by 4% 201,600 * 1.04 = 209,664 Appreciate your help. thanks, ed