Answer:
$400
Step-by-step explanation:
Total Sales Value = No of chocolate cakes × sales price
 = 100 × 25
 = 2,500
Total Costs: 
= materials + direct labor + variable factory overhead + special packaging
= ($12 × 100) + ($5 × 100) + ($3 × 100) + 100
= $1200 + 500 + 300 + 100
= $2,100
Profit = Sales value - Total costs
 = 2,500 - $2,100
 = $400
Note: Fixed costs remain fixed thus will not be affected by acceptance of offer
Variable selling costs will be ignored as they will not be incurred as per the question