Answer: x: 1... y: 2... z: -5
Explanation:
You need to get z by itself. Divide -4 on both sides and z=-5
Then, get y by itself. Move 6x... and -3y=-6x (the zero doesn't matter now)... then divide by 3 and... y=2x
Now, plug y and z into the first equation...
-2x + 3(2x)+5(-5)=-21
Now solve!
-2x + 6x -25 = -21
4x - 25 = -21
4x = 4
x = 1
Now, you can plug x into the third equation to find y...
6(1) - 3y = 0
Solve!
6 - 3y = 0
-3y = -6
y = 2
Now we have all of them!