Constraint Layout DOJO - Solution (STEP 2)

comment.xml

<ImageView
    android:id="@+id/comment"
    android:layout_width="21dp"
    android:layout_height="21dp"
    android:layout_marginTop="12dp"

    android:src="@drawable/ic_comment"
    android:tint="@color/gray"

    app:layout_constraintTop_toBottomOf="@+id/text"
    app:layout_constraintLeft_toLeftOf="@+id/text"
    app:layout_constraintRight_toLeftOf="@id/retweet"
    app:layout_constraintHorizontal_chainStyle="spread_inside"/>

favorite.xml

<ImageView
    android:id="@+id/favorite"
    android:layout_width="21dp"
    android:layout_height="21dp"

    android:src="@drawable/ic_favorite"
    android:tint="@color/gray"

    app:layout_constraintTop_toTopOf="@+id/comment"
    app:layout_constraintLeft_toRightOf="@+id/retweet"
    app:layout_constraintRight_toLeftOf="@+id/share"/>

retweet.xml

<ImageView
    android:id="@+id/retweet"
    android:layout_width="21dp"
    android:layout_height="21dp"

    android:src="@drawable/ic_retweet"
    android:tint="@color/gray"

    app:layout_constraintTop_toTopOf="@+id/comment"
    app:layout_constraintLeft_toRightOf="@+id/comment"
    app:layout_constraintRight_toLeftOf="@+id/favorite"/>

share.xml

<ImageView
    android:id="@+id/share"
    android:layout_width="21dp"
    android:layout_height="21dp"

    android:src="@drawable/ic_share"
    android:tint="@color/gray"

    app:layout_constraintTop_toTopOf="@+id/comment"
    app:layout_constraintLeft_toRightOf="@+id/favorite"
    app:layout_constraintRight_toRightOf="@+id/text"/>