Problems with the percentage layout of the first line of code

In APP / build. Gradle, as written in the book, you should add the following to the dependencies closure

dependencies {
    --- 
    compile 'com.android.support:percent:24.2.1'
    ---
}

If you write directly, you will find an error.

Since the complex used by the reference library before Android studio is upgraded to 3.0 becomes implementation by default, you should write this

implementation 'com.android.support:percent:24.2.1'

But if you write this, you will find a red line below

Please correct any errors