EOQ and cost of capital

Hi Sir,

In the following question about EOQ the idea of the cost of capital was introduced so how can we incorporate the the cost of capital in the EOQ calculation?
or could be other items like Chief buyer’s salary .

Thanks,

(b)
The production manager has established the following information about a major
inventory item.
Purchase price per unit
$480
Annual demand
4,000
Supplier’s delivery costs per order
$10
Chief buyer’s salary per annum
$30,000
Total number of orders placed per annum*
1,000
Annual storage costs per unit
$2
Cost of capital 10% per annum
*Relates to all product lines, not just this one.

What is the economic order quantity for this inventory item?
A 40
B 80
C 200
D 400