$\text{a)}$  

$y=2x-5\mid -y$  

$0=2x-y-5$  

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$\text{b)}$  

$y=\frac{2}{3}x+5\mid \cdot 3$  

$3y=2x+15\mid -3y$  

$0=2x-3y+15$  

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$\text{c)}$  

$y=-x\mid +x$  

$x+y=0$  

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$\text{d)}$  

$y=-\frac{2}{7}x+\frac{3}{14}\mid \cdot 14$  

$14y=-4x+3\mid +4x-3$  

$4x+14y-3=0$  

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$\text{e)}$  

$y=-\frac{1}{3}x+1\mid \cdot 3$  

$3y=-x+3\mid +x-3$  

$x+3y-3=0$  

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$\text{f)}$  

$y=\frac{2}{5}x-2\mid \cdot 5$  

$5y=2x-10\mid -5y$  

$0=2x-5y-10$