Resolved versions for app (26.1.0) and test app (27.1.1) differ : <p>This is the full error-</p>

<pre><code>Error:Execution failed for task ':app:preDebugAndroidTestBuild'.
&gt; Conflict with dependency 'com.android.support:support-annotations' in project ':app'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. See https://d.android.com/r/tools/test-apk-dependency-conflicts.html for details.
</code></pre>

<p>I know that there are a lot of solutions to this type of answers but I am an absolute beginner in android studio and I couldnt understand those solutions like the command line interface interacting with gradle and so on...</p>

<p>I was looking for a simple solution to this problem if there is.
Thanks a lot!</p>
