error when running the 'React-Native Run-android '

• Get more help at https://help.gradle.org

BUILD FAILED in 9s

error Failed to install the app. Make sure you have the Android development environment set up: https://facebook.github.io/react-native/docs/getting-started.html#android-development-environment. Run CLI with --verbose flag for more details. Error: Command failed: gradlew.bat app:installDebug -PreactNativeDevServerPort=8081

FAILURE: Build failed with an exception.

• What went wrong: A problem occurred configuring project ':app'.

  SDK location not found. Define location with an ANDROID_SDK_ROOT environment variable or by setting the sdk.dir path in your project's local properties file at 'F:\projetob\android\local.properties'.

• Try: Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

• Get more help at https://help.gradle.org

BUILD FAILED in 9s

at checkExecSyncError (child_process.js:629:11)
at execFileSync (child_process.js:647:13)
at runOnAllDevices (F:\projetob\node_modules\@react-native-community\cli-platform-android\build\commands\runAndroid\runOnAllDevices.js:94:39)
at process._tickCallback (internal/process/next_tick.js:68:7)