Answer: $30
Step-by-step explanation:
The formula to determine the transfer price is;
Transfer price = Differential cost to selling division + Opportunity cost of selling internally
The Differential cost is the Variable cost of producing the heating units so is $30.
The Opportunity cost of selling internally refers to if any sales will be foregone outside by selling inside. As the Heating Division has sufficient excess capacity, outside sales will not be affected so this cost is $0.
Transfer Price = 30 + 0
= $30