Answer:
the variable cost ratio is 60 % (option d)
Step-by-step explanation:
The variable cost ratio (VCR) represents the ratio of variable costs to sales. Therefore
VCR = (total variable costs)/(total sales)
since
total variable costs = variable costs * services provided = $21/hour * 12000 hours/year = $252000 /year
total sales = price of service * services provided = $35/hour * 12000 hours/year = $420000 /year
thus
VCR = ($252000 /year) / ($420000 /year) = 0.6 = 60 %