1. It's really simple. / It's very easy.
很简单。

2. It's a piece of cake.
小事一桩。

3. It's easy as pie. / It's easy as ABC.
真是易如反掌。

4. It's no big deal!
没什么大不了的！（很简单）

5. It's a no-brainer!
这很简单，不用花什么脑筋的！

6. I can do it with my eyes closed!
我眼睛闭起来都能做！

7. That's no sweat at all!
那一点都不难！

8. Nothing to it!
没什么难的！

9. It's a joke. Anyone can do it.
这很简单。谁都可以做。

10. It's a cinch!
简单的很！