Answer:
25%
Explanation:
New contribution margin = Old contribution margin + Increase
= 135,000 + 30,000
= 165,000
Net Income = Contribution margin - Total fixed expense
= $165,000 - $90,000
= $75,000
ROI = Net income ÷ Average operating assets
= 75,000 ÷ 300,000
= 25%