- ((- 8·x^2·y^2 - 20·x^4·y^3/(- 5·x^2·y^2) - 4·y·(3·x·y)) - (- 8·x^2·y^2 + 4·x·y^2)) + (12·x^2·y - 16·x·y^2)=
= - ((- 8·x^2·y^2 + 4·x^2·y - 12·x·y^2) - (- 8·x^2·y^2 + 4·x·y^2)) + (12·x^2·y - 16·x·y^2)=
= ((8·x^2·y^2 - 4·x^2·y + 12·x·y^2) + (- 8·x^2·y^2 + 4·x·y^2)) + (12·x^2·y - 16·x·y^2)=
=(16·x·y^2 - 4·x^2·y) + (12·x^2·y - 16·x·y^2)=
=8·x^2·y
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$\small -\left\{\left[-8x^2y^2-20x^4y^3÷\left(-5x^2y^2\right)-4y\left(3xy\right)\right]-\left(-8x^2y^2+4xy^2\right)\right\}+\left(12x^2y-16xy^2\right) =$
$\small = -\left\{\left[-8x^2y^2+4x^2y-12xy^2\right]+8x^2y^2-4xy^2\right\}+12x^2y-16xy^2 =$
$\small = -\left\{-\cancel{8x^2y^2}+4x^2y-12xy^2+\cancel{8x^2y^2}-4xy^2\right\}+12x^2y-16xy^2 =$
$\small = -\left\{4x^2y-16xy^2\right\}+12x^2y-16xy^2 =$
$\small = -4x^2y+\cancel{16xy^2}+12x^2y-\cancel{16xy^2} =$
$\small = -4x^2y+12x^2y =$
$\small = 8x^2y $