How do I get rid of the error while compiling?

[Theera]

Hi all,
I 've found this problem for several times as attached picture. Please help me.

 

[Erel]

There is a problem with your path configuration. You can either download the latest SDK Manager or search for dx.jar and copy it to platform-tools\lib.

 

[Theera]

There is a problem with your path configuration. You can either download the latest SDK Manager or search for dx.jar and copy it to platform-tools\lib.

Hi Erel,
After I copied dx.jar into the folder lib which created by myself within the directory platform-tools. I 've a new error message.
(duplicated)

 

[Erel]

Somehow ahtranslate library was added twice to the project.

 

[Theera]

Somehow ahtranslate library was added twice to the project.

Hi Erel,
You are right. I have converted the classes of ahatranslate to be library and checked it ,but don't remove all of them.
I think that it should has warning message and set priority of library is The first or The second.