John hired Tim to type text. John made a $1,000 deposit, estimating of half of the total cost at their agreed per page price, with the balance due on delivery of the last volume, with the balance to be adjusted according to the actual page count.Tim delivered all but the last volume, and sent a final bill with the adjusted balance due based on the final page count to John, with a note indicating that the final volume would be delivered upon payment in full. John refuses to pay. If Tim sues, what will be the result?