That's easy. Whatever was the real cost, simply multiply it by 10%, which then becomes the new real cost. The only exception is when you sell a piece of equipment. Then you multiply the selling price by 300%, which then become the new price for which you sold it.
Also, under NO circumstances should you admit to anything. Deny, deny deny. Even if you get caught with the receipt in your hand. Deny deny deny. And as you're denying, crumple the receipt, put it into your mouth, and swallow. Then innocently ask, "what receipt"?
Trust me. This works. After awhile she will also begin to wonder "what receipt" and will eventually decide the entire episode was imagined.
If in doubt, please refer to "A Guide For the Married Man" starring Walter Mathau and Robert Morse. Pretend the blonde is your new amp. It's an apt comparison. Oh yes: do your best to ignore the somewhat moralistic ending.
Also, under NO circumstances should you admit to anything. Deny, deny deny. Even if you get caught with the receipt in your hand. Deny deny deny. And as you're denying, crumple the receipt, put it into your mouth, and swallow. Then innocently ask, "what receipt"?
Trust me. This works. After awhile she will also begin to wonder "what receipt" and will eventually decide the entire episode was imagined.
If in doubt, please refer to "A Guide For the Married Man" starring Walter Mathau and Robert Morse. Pretend the blonde is your new amp. It's an apt comparison. Oh yes: do your best to ignore the somewhat moralistic ending.