Answer:
Variable cost= $42
Explanation:
Giving the following information:
Each unit is sold for $50
Direct material worth $30
Direct labor worth $5.
Manufacturing overhead cost is $10 per unit of which 70% is variable.
The incremental cost is the variable cost (there is available capacity)
Variable cost= direct material + direct labor + variable manufacturing overhead = 30 + 5 + (10*0.7)= $42