That settles it, then. 就这么定了。
原音重现：
A: I'll cook dinner on Monday, Wednesday and Friday, and you cook the other nights.
我周一、三、五做晚饭，其他曰子你来做吧。
B: T hat settles it, then. We'll share the responsibility of cooking.
就这么定了！我们就这样轮流做饭吧。