Answer:
incremental per gallon increase in net income = Â $18.30
the total increase in net income = $732,000
Explanation:
incremental per gallon increase in net income
Consider only the Incremental Costs and Revenues. Fixed manufacturing overheads are irrelevant for this decision.
Sales                            $15.50
Direct materials                    ($1.70)
Direct labor                       ($0.60)
Variable manufacturing overhead    ($0.50)
Total                             $18.30
the total increase in net income
total increase = incremental per gallon × number of gallons
            = $18.30 × 40,000
            = $732,000