2z+(2z-3)=21

Solution for 2z+(2z-3)=21 equation:

Simplifying
2z + (2z + -3) = 21

Reorder the terms:
2z + (-3 + 2z) = 21

Remove parenthesis around (-3 + 2z)
2z + -3 + 2z = 21

Reorder the terms:
-3 + 2z + 2z = 21

Combine like terms: 2z + 2z = 4z
-3 + 4z = 21

Solving
-3 + 4z = 21

Solving for variable 'z'.

Move all terms containing z to the left, all other terms to the right.

Add '3' to each side of the equation.
-3 + 3 + 4z = 21 + 3

Combine like terms: -3 + 3 = 0
0 + 4z = 21 + 3
4z = 21 + 3

Combine like terms: 21 + 3 = 24
4z = 24

Divide each side by '4'.
z = 6

Simplifying
z = 6