Answer
$(\frac{56}{13},-\frac{7}{13},\frac{35}{13})$
Work Step by Step
1. Multiply -1 to the first equation, then add to the third, we get $x-5y=7$
2. Multiply 3 to the second equation, then add to the first, we get $-4x+7y=-21$
3. Multiply 4 to the equation in step1, then add to the equation in step2, we get $-13y=7$, thus $y=-\frac{7}{13}$
4. Back substitute to get $x=7+5y=\frac{56}{13}$ and $z=-7+2x-2y=-7+2(\frac{56}{13})-2(-\frac{7}{13})=\frac{35}{13}$
5. The solution is $(\frac{56}{13},-\frac{7}{13},\frac{35}{13})$
