18. Buffalo Payroll & Billing produces office machinery. High and low level of activity last year was 60,000 units of product produced in May and 20,000 units produced in November. Machine maintenance costs were $52,000 in May and $20,000 in November. Using the high-low method, determine an estimate of total maintenance cost for a month in which production is expected to be 45,000 units. A) $45,000 B) $48,000 C) $39,000 D) $40,000