LogFAQs > #955574776

Ignoring the ridiculousness of the setup in real-world terms, and looking at this purely as a math problem, you should pay $30 back into the joint account.

Breakdown:

1. You have taken $40 out of the joint account to buy the cookies. Don't think of this like having each already paid $20. It's more like you have borrowed that money and now you each need to pay it back.
2. You agree cover 75% of the price, and your wife 25%. These values should be coming out of your individual accounts.
3. Your wife puts $10 back into the joint account, covering the loss that she has offered to repay.
4. At this point, the join account is $30 short, all of which you have agreed to cover from your own money.
5. You pay $30 back into the joint account, covering the loss you offered to pay.

In the end, the join account was charged a total of $40 for the initial purchase, and then a total of $40 was deposited back, leaving it square. $30 has come out of your personal account and $10 has come out of your wife's personal account, matching the amounts you've each agreed upon.

EDIT: Alternatively, you can look at the initial purchase as if each of you has paid $20 for the cookies. In this case, your wife has over-paid by $10 and you have under-paid by $10. Give your wife's personal account $10 out of your own personal account to fix this.

---

PSN ID: Aristoph
https://www.youtube.com/channel/UCj5ydFYxnEODxpQeBswmiAA