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Now, we have z = 4 and y = 2 ...  Stick them both into the top equation and we'll get x!

2x - y + 6z = 20 ... 2x - 2 + 6 ( 4 ) = 20 ... 2x - 2 + 24 = 20 ... 2x + 22 = 20 ... 2x = -2 ... x = -1

So, x = -1, y = 2 and z = 4.  Since this is a point in space, we write the answer as a 3-D coordinate: 

(-124)

Yeah, that was just the END of one of these problems!  Really, it just looks like a lot because of all my explaining.


TRY IT:

Just work your way back up:

x + 4y - 5z = 39

7y + 2z = 11

y = 3