(一).We have a deal? 就这么定了？

This is a way to make certain an agreement was made. It is like saying “Do you agree to this?"

原音重现：

A: We have a deal?
就那么办？
B: Sure, I'll agree to that.
当然，我同意了。

美剧表达：

All right, we have a deal? 好的，就那么 办吗？
Do we have a deal or not? 我们就这么说 定了？

(二).I thought we had a deal.我认为我们已经说好了的。
Usually this is said when one person breaks an agreement. The other person may become angry, and this is a way of expressing "I thought I could trust you to honor the agreement."

原音重现：

A: I thought we had a deal.
我认为我们已经说好了的。
B: Well, I changed my mind about it.
哦，我改变主意了。

美剧表达：
How could you betray me like this? We had a deal, and you stabbed me in the back.你怎么能如此背叛我呢？我们不是 约好了吗？你竟然背叛了我。
You have to help me out here. I thought we had a deal.你一定要帮我，我想我们 有约在先的。