Not sure if my math is wrong

[BaldLilFairy]

Im really hoping my professor isnt being sadistic and having all four of the problems have the answer of no solution.
Please review and let me know if my math is wonky.

Question:
Sovle each system by any method, if there is no solution or if the system is dependent, so state.

3x - 4y + 4z = 7 1
x - 2y - 2z = 2 2
2x - 3y + 6z = 5 3

This is what I did:
3x - 4y + 4z = 7 1
-3x + 6y - 6z = -6 2
2y - 2z = 1 4

-6x + 8y - 8z = -14 1
6x - 3y + 6z = 5 4
5y - 2z = -9 5

-2y + 2z = 6 4
5y - 2z = -9 5
y = -1

-2(-1) + 2z = 6
2z = 4
z = 2

3x - 4(-1) + 4(2) = 7
3x + 4 + 8 = 7
3x = -5
x = -5/3

The Check
3(-5/3) - 4(-1) + 4(2) = 7
-5 + 4 + 8 = 7
7 = 7 true

-5/3 - 2(-1) - 2(2) = 2
-5/3 +2 -4 = 2
-1/3 = 2 false

2(/5/3) - 3(-1) + 6(2) = 5
-10/3 +4 + 12 = 5
44 = 15 false

 

[Denis]

3x - 4y + 4z = 7 1
x - 2y - 2z = 2 2
2x - 3y + 6z = 5 3

This is what I did:
3x - 4y + 4z = 7 1
-3x + 6y - 6z = -6 2 ***********
2y - 2z = 1 4

************* should be -3x + 6y + 6z = -6