Assume for purposes of this question only that after seeing Kim's estimate, Sean realizes that he'd like to engage Josh's less expensive snow removal service and calls Josh on Tuesday, October 19, 2021. After exchanging hellos, Sean says the following to Josh, "Josh, I'm accepting your offer to do the snow clearing at the Quakertown this Winter, provided that you also snow plow the walkways and shovel the steps at the Quakertown too. I forgot to discuss that with you when we met last Wednesday." At this point, do Sean and Josh have a valid contract? Why or why not? If they have a valid contract, what are its terms?