Question 1054228
Multiply eq. 3 by 2 and subtract from eq. 1,
{{{2x+3y+4z-2x-8y-2z=12-10}}}
4.{{{-5y+2z=2}}}
Multiply eq. 3 by 3 and subtract from eq. 2,
{{{3x+y+z-3x-12y-3z=4-15}}}
5.{{{ -11y-2z=-11}}}
Add eqs. 4 and 5,
{{{-5y+2z-11y-2z=2-11}}}
{{{-16y=-9}}}
{{{y=9/16}}}
So then working backwards,
{{{-5(9/16)+2z=2}}}
{{{-45/16+2z=2}}}
{{{2z=32/16+45/16}}}
{{{2z=77/16}}}
{{{z=77/32}}}
and finally,
{{{x+4(9/16)+77/32=5}}}
{{{x+36/16+77/32=160/32}}}
{{{x=160/32-72/16-77/32}}}
{{{x=11/32}}}