a的平方*b^3ab+5*a的平方*b@4ab
=a^2*(b+3ab)+5a^2*(b-4ab)
=a^2b+3a^3b+5a^2b-20a^3b
=6a^2b-17a^3b
=6*(5^2)*3-17*(5^3)*3
=5895