<Button
android:layout_width="300dp"
android:layout_height="70dp"
android:background="@color/colorAccent"
android:drawableLeft="@drawable/ic_dashboard_black_24dp"
android:text="start"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />