Swanson and Associates presently leases a copy machine under an agreement that calls for a fixed fee each month and a charge for each copy made. Swanson made 7,000 copies and paid a total of $360 in March; in May, the firm paid $280 for 5,000 copies. The company uses the high-low method to analyze costs.

Swanson's variable cost per copy is:

$0.040.

$0.051.

$0.053.

$0.056.

an amount other than those given above.