①4a^(2/3) b^(-1/3) ÷[-2/3a^(-1/3)b^(-1/3)]
=-4a^(2/3) b^(-1/3) ×[(3/2)a^(1/3)b^(1/3)]
=-6a
②【-2x^(1/4) y^(-1/3）][3x^(-1/2)y^(2/3）][-4x^(1/4)y^2/3）]
=24x^(1/4 -1/2 +1/4) y^(-1/3+2/3 +2/3)
=24y