Answer:
Maintenance cost at 27000 = $76,500
correct option is B $76,500
Step-by-step explanation:
given data 
maintenance costs = $63,000
output level = 18,000 units
mixed cost, and the fixed = $36,000
total maintenance cost output level = 27,000 units
solution
we know here that Variable costs at 18000 units i s
Variable costs at 18000 units = 63000 - 36000
Variable costs at 18000 units = $27000 
so Variable unit cost is = 

Variable unit cost = 1.5 
and
Maintenance cost at 27000 units will be 
Maintenance cost at 27000 = Fixed cost + 27000 × Unit variable cost 
Maintenance cost at 27000 = 36000 + (1.5 × 27000)
Maintenance cost at 27000 = $76,500
correct option is B $76,500