Simple three way calculation

Question

Three roommates share household supplies and split the costs. Each buys items and adds the items to the ledger. At the end of the month they reimburse each other for expenses on the ledger.

Adam spent $27

Eve spent $9

Satan spent $36

Who owes who what?

Note: They share costs at a rate of about 30% or 1/3 (divide by 3)

Answer 1

(27+9+36)/3 = 24

36-24 = 12

27-24 = 3

Eve owes Satan $12 and Adam $3

Note that 9 + 12 + 3 = 24