Answer:
To solve for z you need to get it by itself and have the other half of the equal sign simplified.
42=-7(z-3)
42=-7z+21 (you would distribute the -7 through the parentheses.)
21=-7z ( you would then subtract 21 from both sides)
-3=z ( last your would divide -7 to both sides to get z by itself)
z=-3
Explanation: