A maintenance company charges a monthly fee to clean office buildings. The fee is based on the number of employees in the office. An office with 15 employees pays $150 per month while an office with 27 employees pays $246 per month. Which of the following functions represents the relationship between the monthly cost and x, the number of employees? A. f(x) = 8x
B. f(x) = 8x + 30
C. f(x) = 12x + 94
D. f(x) = 6x + 84