III. On June 15, Valerie entered into a written and signed agreement with Justin. Justin agreed to replace the cesspool behind Valerie's home for the sum of $20,000 and to complete the work on or before July 1 so that Valerie could host the July 4th holiday barbecue comfortably in in her backyard. Before entering into the agreement, Justin tested the soil and area around the existing cesspool to satisfy himself as to the character of the ground beneath the surface and also so to produce a correct estimate of costs.

Justin commenced work on June 25, and he expected the job to be completed in only a couple of days. But after only two hours of excavation work to remove the existing cesspool, Justin encountered problems with the ground around the cesspool. The ground proved significantly more challenging to remove. That evening, Justin removed his equipment and advised Valerie that the project couldn't continue at their agreed price of

$20,000. He now needed more employees and equipment than originally planned to meet the July 1 deadline.

Fearing that her barbecue plans might be ruined and that she wouldn't find an alternate contractor on such short notice, Valerie told Justin that she would pay an extra $5,000 only if he could get the work completed on time. Justin agreed and completed the work on July 1 as originally planned.

A)Upon completion of the work, Justin presented Valerie with an invoice for $25,000. Valerie refused to pay it, insisting that she had never become obligated to pay the extra $5,000, and demanded that Justin accept $20,000, originally contracted. Justin brought an action to recover $25,000 based on an alleged breach of contract by Valerie. What verdict? Fully explain. (10 credits)

B) Assume instead: that Justin wrote an email to Valerie to memorialize her promise to pay the extra $5,000. What result? Fully explain. (10 credits)

C) Assuming instead: that Valerie, upon receiving Justin's invoice, sent him a check for $22,500; and that she enclosed a separate note that stated "Let's split the difference - payment in full attached"; and that Justin endorsed and deposited the check without further notation on the check. After depositing the check, Justin sues Valerie for the $2,500 balance. What result? Fully explain. (10 credits)