(2a+3b-2ab)-(a+4b+ab)-(3ab+2b-2a)
=2a+3b-2ab-a-4b-ab-3ab-2b+2a
=(2a-a+2a)+(3b-4b-2b)+(-2ab-ab-3ab)
=3a-3b-6ab
=3(a-b)-3ab
=3×5-3×1
=12