<p>
[quote]
"Yeah, I overanalyzed this question too.
I was going to try the make x=9 method, but i ran out of time before I got to an answer =(</p>
<p>Does anyone remember if the question had 3 equations or 4? If there were only 3, it's pointless trying to solve using systems as you need 4 equations to solve for 4 variables anyways. -.-;;"
[/quote]
</p>
<p>Wrong, solving a system would be very helpful. This is what many people fail to see. There is a constraint on every variable... they must be an integer element of the interval [0,9] which means putting the equations in terms of one variable was very helpful.</p>
<p>As I pointed out before, it allows you to determine the value of y as 4 and then you can do the rest through the original equations.
[quote]
Put x and z in terms of y.
x=3(y-1)
z=y-4</p>
<p>y<=4 with the first one and y>=4 with the second one... hence y=4.
[/quote]
</p>
<p>I hope I didn't come off as too brusque. If I did, sorry. :D</p>