Given the equation system:
8y + 4z = 7 eq. 1.
6y – 8z = 41 eq. 2.
First we multiply equation 1 by 2, as follows:
16y + 8z = 14 eq. 3.
Now we substract eq 2 and 3:
16y + 8z = 14
6y – 8z = 41
___________
22y = 55
y = 5/2
Finally, we replace the y - value on eq 2:
6(5/2) - 8z = 41
15 - 8z = 41
-8z = 41 - 15
-8z = 26
z = -13/4