那就这么定了英文怎么说

"那就这么定了"在英语中可以说作"That's settled then."。

来源：这个短语是由"that"（那）和"settle"（定下，解决）组成的。

例句：

"We've agreed on a plan, so that's settled then."
(我们已经就计划达成了一致，那就这么定了。)
"Let's put this matter to rest, that's settled then."
(让我们把这件事情解决了，那就这么定了。)
"I'll take care of it, that's settled then."
(我会处理这件事，那就这么定了。)