Question

What is the answer to y+2x+3 y-2x=-1

Answer 1

$\left \{ {{y+2x=3} \atop {y-2x=-1}} \right.$
$y+y+2x+(-2x)=3+(-1)\\\\ 2y+2x-2x=3-1\\\\ 2y=2 \ |:(-2)\\\\ y=1$
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$y+2x=3$

$1+2x=3 \ |-1\\\\2x=2 \ |:2\\\\ x=1$
$\left \{ {{x=1} \atop {y=1}} \right.$

Answer 2

Hello : 
y+2x=3 ...(1)
y-2x=-1...(2)
by (1) : y =-2x+3
by(2) : y=2x-1
2x-1=-2x+3
2x+2x=3+1
4x=4
x=1
y= 2(1)-1=1