Markson and Sons leases a copy machine with terms that include a fixed fee each month plus a charge for each copy made. Markson made 10,000 copies and paid a total of $850 in January. In April, they paid $570 for 6,000 copies. What is the variable cost per copy if Markson uses the high-low method to analyze costs? If required, round your answer to two decimal places. Variable cost $ per copy