You don't need 3 equations to get a general solution. To do this use the equations x-3y-z=0 and -x+2y+0z= -3. Start out by letting z = t. Then solving those 2 equations simultaneously, your x's cancel out leaving you with -y-z=-3. But since z=t, then -y=-3+t or y=3-t. Now sub that in for y in the first equation, along with the fact that z=t to get x-3(3-t)-t = 0 and solve for x. x=9-2t. So a general solution for this would be (9-2t, 3-t, t)
Maybe rewrite it simpler?
The second one, functions cannot have multiple y values for one x value
Hey!
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The constant of proportionality is 0.27!
We could write a word problem for this. Like:
Jared had paid $0.27 for one pencil. How much would it cost to buy 5 pencils?
0.27 x 1 = $0.27
0.27 x 2 = $0.54
0.27 x 3 = $0.81
0.27 x 4 = $1.08
0.27 x 5 = $1.35
We can see that if Jared bought 5 pencils for $1.35. Since the proportionality is 0.27 just multiply how many times you need to.
We could also write this as: 
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Hope This Helped! Good Luck!
Answer:
a = 1 and b = 14 or a = 14 and b = 1
Step-by-step explanation:
This means that ab = 14 and a + b = 15. Simple guess and check reveals (1, 14) or (14, 1).