原式=5abc-[2a^2b-(3abc-4ab^2+a^2b)]
=5abc-(2a^2b-3abc+4ab^2-a^2b)
=5abc-(a^2b-3abc+4ab^2)
=5abc-a^2b+3abc-4ab^2
=8abc-a^2b-4ab^2
=48+4-16
=36