app/build.gradle error

implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'com.android.support:appcompat-v7:23.+'

jre -> jdk

7.23   < --  설정한 api 버전숫자로 변경

Make sure you are using the same compile SDK version and the app compat version. Check your gradle file.

For example, if you are compiling with SDK 23

compileSdkVersion 23

You must use the same app compat version 23.x.x

compile 'com.android.support:appcompat-v7:23.4.0