$78 is the Relevant cost per unit of part A12E when the Bramble Corp buys the part from an outside supplier.
Step-by-step explanation:
Relevant cost per unit of part A12E
Direct materials+Direct labor +Variable overhead +
(Fixed overhead - Avoidable fixed overhead )
= $ 50000 + $155000 +$70000 + $115,000 ($175000 - $60000)
= 390,000 ÷ 5000 units = $78
Relevant cost per unit of part A12E is $78 when the Bramble Corp buys the part from an outside supplier.