Failed to resolve: com.android.support:appcompat-v7 24.0.1

You can also write like this:

allprojects {
        repositories {
            jcenter()
            maven {
                url "https://maven.google.com"
            }
        }
    }

try

  compile 'com.android.support:appcompat-v7:24.2.1'

EDIT

For sdk 27

buildToolsVersion "27.0.3"

implementation "com.android.support:appcompat-v7:27.1.1"

Try adding jcenter like this way

repositories {
    jcenter {
        url "http://jcenter.bintray.com/"
    }
}

Rather than

  repositories {
        jcenter()
    }