Jensen (defendant) contracted with Marton Remodeling (Marton) (plaintiff) to remodel his house. When Marton sought to collect payment, Jensen claimed that the time charged for was excessive. Jensen then sent a check to Marton for what he felt was the appropriate amount and wrote on the check a condition to the effect that it was full payment for Marton’s services. Marton cashed the check and wrote “not full payment” below Jensen’s written condition. Marton then brought suit to recover the remaining amount. The trial court found in favor of Marton and Jensen appealed.