Question 98227
Hi,<br />

I don't know how you've been taught to do these, but by the sounds of it, it's by subtraction. I'm going to try and eliminate z by using the second equation. Both the first and second equations have a single z in, so if I subtract them, I will cancel the z term.<br />

(3x+4y+z) - (2y+z) = 7 - 3
3x+2y = 4<br />

The third equation has 8 zeds in it. So we need to subtract the second equation 8 times (or subtract 8* the second equation) from the third equatuation to get rid of all the zeds.<br />

(-5x+3y+8z) - 8(2y+z) = -31 - 8*3
-5x-13y = -55
5x+13y = 55<br />

So there I have eliminated z, can you now either eliminate x or y from these two equations to get the answer?<br />

Kev