Error comes while adding Admob in android studio

Question

This is my gradle code of file

apply plugin: 'com.android.application'

    android {

        compileSdkVersion 24

        buildToolsVersion "24.0.3"
        defaultConfig {
            applicationId "com.example.administrator.shawarma"
            minSdkVersion 15
            targetSdkVersion 24
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
            multiDexEnabled true
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            }
        }}dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
            exclude group: 'com.android.support', module: 'support-annotations'
        })
        compile 'com.android.support:appcompat-v7:24.2.1'
        compile 'com.google.firebase:firebase-ads:10.0.1'
        compile 'com.google.android.gms:play-services-appindexing:8.4.0'
        testCompile 'junit:junit:4.12'}apply plugin: 'com.google.gms.google-services'

it's showing error in log cat like this while running

Error:Execution failed for task ':app:transformClassesWithJarMergingForDebug'. > com.android.build.api.transform.TransformException: java.util.zip.ZipException: duplicate entry: com/google/android/gms/internal/zzqb.class