Answer:
Net increase in operating income = $1,200
Step-by-step explanation:
Contribution margin per unit = $150 - $75 = $75 per unit
if marketing expenses increase by $6,300, the total number of units sold will incerase by 100 units. Differential increase in contribution margin = $75 x 100 = $7,500. Differential increase in fixed expenses = $6,300. Net increase in operating income = $7,500 - $6,300 = $1,200