2x -y +z = 7
2x + 4y - 2z = 0
x-y + 3z = 2

x = 3

y = -2

z = -1.

Step-by-step explanation:

2x -y +z = 7

2x + 4y - 2z = 0

x-y + 3z = 2

Subtracting the second equation from the first:

-5y + 3z = 7  (A)

Multiply the third equation by -2 and adding this to the second equation:

6y -8z = -4 (B)

Multiply A by 8 and B by 3, we get

-40y + 24z = 56

18y - 24z = -12       Adding:

-22y = 44

y = -2

So substituting for y in A:

-5(-2) + 3z = 7

3z = 7-10 = -3

z = -1.

Finally, substituting for y and z in the first equation:

2x -(-2) + (-1) = 7

2x + 2 - 1 = 7

2x = 7 - 1 = 6

x = 3.

nothjing

step-by-step explanation:

answer: all of the odd numbers were opened

the first person was the one that was opening all of the lockers. since one is odd, this causes all of the odd number lockers to be opened in the end.