Solve for both systems: 7y+z=42 and 2y + z = 12

7y+z=42

7y-7y+z=42-7y

z=42-7y

2y + z = 12

2y + 42-7y = 12

42-5y = 12

42-5y-42 = 12-42

-5y=-30

-5y/-5=-30/-5

y=6

z=42-7y

z=42-7(6)

z=42-42=0