The Valley Company is a merchandising firm that sells a single product. The company's revenues and expenses for the last three months are presented below: VALLEY COMPANY Comparative Income Statement for the Second Quarter

	April	May	June
Sales in units	5,000	6,000	7,320
Sales revenue	$700,000	$840,00	$1,024,800
Less: cost of goods sold	280 ,000	336,000	409,920
Gross margin	420,000	504,000	614,880
Less: operating expenses
Shipping expense	60,000	70,000	80,000
Advertising expense	80,000	70,000 80,000	80,000
Salaries and commissions	250,000	200,00	280,000
Insurance expense	9,000	9,000	9,000
Depreciation expense	42,000	42,000	42,000
Total operating expenses	441,000	401,000	491,000
Net income (loss)	$(21,000)	$103,000	$123,880

Required: a. Determine which expenses are mixed and, by use of the high-low method, separate each mixed expense into its variable and fixed components. State the cost formula for each mixed expense. b. Compute the company's total contribution margin for May.