- The correct form to fill the blanks of the following independent cases is:
 
Case Revenues variable Fixed Total operating contribution 
 cost cost cost income margin Contribution
a 2400 600 200 800 1600 75% 1800
b 2500 1400 200 1600 900 44% 1100
c 500 300 200 500 0 40% 200
d 1200 900 200 1100 100 25% 300
The below formulas should be used:
-  Contribution = Revenues - variable cost. 
 
- Contribution margin = contribution ÷ revenue. 
 
- Operating income = Revenue - total cost 
 
- Total cost = fixed cost + variable cost