$2\cdot\left(2x-3y\right)-6x+y$

$-3m\cdot\left(m-n+20\right)-4m\cdot\left(2m+8n-3\right)$

$9x-2\cdot\left(x-3y\right)+4\cdot\left(y+4x\right)$

$\frac12\cdot\left(2x-4\right)-5\cdot\left(2x+8\right)+\frac14\cdot\left(12x-4\right)$

$\left(a+b\right)\cdot\left(m-n\right)$

$\left(4{,}2u-2{,}4v\right)\cdot\left(5u-10v\right)$

$\left(x+2y\right)\cdot\left(3a+b+2c\right)$

$16n^2+\left(2+2n\right)\cdot\left(8n+5\right)+4n^2-15$

$\left(2a+5b-c\right)\cdot\left(3a-b\right)$

$\left(4x-3y\right)\cdot\left(y+x\right)+\left(8x+2y\right)\cdot\left(3x+4y\right)$

$2r^2+\left(2r-2s\right)\cdot\left(4r+3\right)+s^2-6\mathrm{rs}$

$\left(4x+2y\right)\cdot\left(x-y\right)-2\cdot\left(x+y\right)\cdot\left(x-y\right)$