The following information is available for a company's cost of sales over the last five months.

Month	Units sold	Cost of sales
January	400	$31,000
February	800	$37,000
March	1,600	$49,000
April	2,400	$61,000

Using the high-low method, the estimated variable cost of sales per unit sold is:

rev: 10_10_2015_QC_CS-29295

$25.42

$77.50

$34.23

$15.00

$30.62