Question

$\left \{ {{y-2x=1} \atop {6x-y=7}} \right.$

Answer 1

y=1+2x
6x-1-2x=7   4x-1=7
4x=8
x=2
y=1+2*2
y=1+4
y=5

Answer 2

{y-2x=1
{6x-y=7

{-2x+y=1
{6x-y=7
  4x /=8
x=8/4
x=2
din y-2x=1
rezulta y-2·2=1
y=1+4
y=5