Variable costs as a percentage of sales for Leamon Inc. are 75%, current sales are $600,000, and

Question:

Variable costs as a percentage of sales for Leamon Inc. are 75%, current sales are $600,000, and fixed costs are $110,000. How much would operating income change if sales increase by $50,000?
a. $12,500 increase
b. $37,500 decrease
c. $37,500 increase
d. $12,500 decrease