How do I do the calculations for this questions?

Problem 8-5
Costcutin Co.
		Product
	A	B	C
Total sales	$1,537,280	$933,600	$1,397,120
Total quality costs
as % of sales	21%	18%	12%
External failure	30%	19%	10%
Internal failure	55%	31%	28%
Appraisal	11%	39%	36%
Prevention	4%	11%	26%

5. Analyze the cost data in the Excel workbook C08Data.xls x for the Costcutin Co. What percent of sales are represented by each category of cost? What are the implications of these data for management