Au あう

Verb (added to other verbs) meaning: each other, reciprocally.

After conjunctive form of verb

助けあうことが大切です。

Tasukeau koto ga taisetsu desu.

It is important to help each other.

その問題について話しあえば解決できると思います。

Sono mondai ni tsuite hanashiaeba kaiketsu dekiru to omoimasu.

If you talk with each other about the problem, I think you can solve it.