那你后给我打电话。这个句子是有问题的，我们可以说，那你忙完后给我电话

As Cherry said, 那你‘后’给我打电话，what 后 or 后 what. It's a complete sentence and feels weird. From the context, 'B is busy working.' A wants B to call A when B has finished B's work. So I would prefer to say '好的，那你忙完后给我打个电话。'

This sentence ought to be : 那以后给我打电话。Not 你后 You translate it correct.

The sentence is correct,but you can use 稍后 to instead of 以后,it means " a little bit later" 那你稍后在给我打电话 稍后 shāo hòu

A: 你忙么？ B: 忙，在办公室呢 A: 那你忙完给我回个电话吧？