I would note all amounts in the contract and also the yearly interest of 15%. Also note that Sam will bring the law suit when Jerry breaches the contract and that the costs of this law suit will be for Jerry.
Both Sam's and Jerry's name underneeth with both signatures.
I think we should note everything I put in my last message and work it out a little more.
And make sure Jerry and Sam sign it before he gets the money.
Maybe also add a fine when Jerry is late with a payment.
And note what the terms of breaching the contract is.