Question 10314
To avoid confusion, remove the parentheses first, working the problem on the inside of the brackets first.

-[2z - (5z+2)] = 2 + (2z +7) 
-[2z - 5z - 2] = 2 + 2z + 7


Combine like terms:
-[-3z - 2] = 9 + 2z


Now remove the brackets, the same as parentheses:
3z + 2 = 9 + 2z


Get the variables all on the left side by subtracting 2z from each side:
3z - 2z + 2 = 9 + 2z - 2z
z + 2 = 9


Subtract 2 from each side:
z + 2 - 2 = 9 - 2
z = 7


R^2 at SCC