Surya wants to renovate the bathroom and kitchen in his home, and he hires Kayla for this work. They enter into a contract after agreeing to a cost of $30,000. However, once Kayla starts work, she realizes that it will cost $15,000 extra to complete the work that she promised. To show good faith to Surya, Kayla tells him that she will split the added cost with Surya and asks Surya for the additional $7,500. Surya tells Kayla that he's not happy about this at all, but Kayla tells him that she cannot continue with the renovation if he doesn't split the additional costs with her.

After speaking to other contractors and realizing that they would charge much more than $7,500, Surya calls up Kayla and agrees to pay the additional $7,500, and then Kayla sends Surya an email confirming that she will pay half of the extra $15,000.

After the renovations are completed, Surya refuses to pay the $7,500. Kayla sues Surya for breach of contract. Who wins? Please explain fully.