Answer:
Effect on income= $73,600 increase
Step-by-step explanation:
Giving the following information: 
Contribution margin $ 112 
Increase in variable cost= $8 per unit. 
Decrease in fixed costs= $100,000 per month. 
Increase in sales unit= 500 units
To calculate the effect on income, we need to use the following formula:
Effect on income= effect on total contribution margin + decrease in fixed costs
Effect on income= 500*104 - 9,800*8 + 100,000
Effect on income= $73,600 increase