Highest copies month = august = 105,000 =>$6,000.

lowest copies month = february = 35,000 =>$3,200.

variable cost per copy = difference in cost / difference in copies

=> ($6,000 - 3,200) / (105,000 - 35,000)

=>$2,800 / 70,000

=>$0.04 per copy.

variable cost per copy = $0.04 per copy.