Runaround Corporation sells running shoes and during January they ran production machines for 20,000 hours total and incurred $9,000 in maintenance costs. During July they ran production machines for 14,000 hours total and incurred $7,200 in maintenance costs. Based on this data, what is the variable maintenance cost per machine hour? OA. OB. OC. O D. $0.30 per machine hour $0.51 per machine hour $3.33 per machine hour $0.45 per machine hour