To solve this, you need to find the value of "z" by isolating/getting the variable "z" by itself in the equation:
6z + 4 = 8z Subtract 6z on both sides to get "z" on one side of the equation
6z - 6z + 4 = 8z - 6z
4 = 2z Divide 2 on both sides to get "z" by itself
2 = z
12z = ? Since you know z = 2, substitute/plug in 2 for "z" in the equation
12(2) = ?
24