①(3x-2)(4x+5)
=12x^2+15x-8x-10
=12x^2+7x-10
②(1/3x-1/2y)(1/2y-1/3x)
=1/6xy -1/9x^2 -1/4y^2 +1/6xy
=1/3xy -1/9x^2 -1/4y^2