Question 850182
There are appear to be three mistakes.
1) Z and z are not the same variable. 3x + y - 2Z = 1
2) 4x + 8y + 4 = 8 there is no z in this equation
3) It is Cramer's rule not Crammer's rule
I removed  4x + 8y + 4 = 8 and used z instead of Z in 3x + y - 2Z = 1
With out the last equation, the answers are 
x = 66/73,   y = -5/73,   z = 60/73