\(A=12x^3:4x-8x:4x-4x(3x+\dfrac{1}{4})\\=(12:4)(x^3:x)+(-8:4)(x:x)+(-4x\cdot 3x)+(-4x\cdot\dfrac{1}{4})\\=3x^2-2-12x^2-x\\=-9x^2-x-2\\---\\B=(3x^3:x)-(2x)^2+x^4:(2x^2)\\=(3:1)(x^3:x)-4x^2+(1:2)(x^4:x^2)\\=3x^2-4x^2+\dfrac{1}{2}x^2\\=\dfrac{1}{2}x^2\\---\)
\(C=(3x^3y^2:x^2y^2)-5x^2y^3:xy^2+4x^3y^3:2x^2y^3\\=(3:1)(x^3:x^2)(y^2:y^2)+(-5:1)(x^2:x)(y^3:y^2)+(4:2)(x^3:x^2)(y^3:y^3)\\=3x-5xy+2x\\=5x-5xy\\---\\D=(-\dfrac{2}{3}x^5y^2):(-6x^2y^2)+\dfrac{3}{4}x^4y^3:(-6x^3y^2)-\dfrac{4}{5}x^3y^4:xy^3\\=[-\dfrac{2}{3}:(-6)](x^5:x^2)(y^2:y^2)+[\dfrac{3}{4}:(-6)](x^4:x^3)(y^3:y^2)+(-\dfrac{4}{5}:1)(x^3:x)(y^4:y^3)\\=\dfrac{1}{9}x^3-\dfrac{1}{8}xy-\dfrac{4}{5}x^2y\)
#\(Toru\)
