$$ \begin{aligned} 10 &= -2(z+3)&& \text{simplify right side} \\[1 em]10 &= -(2z+6)&& \\[1 em]10 &= -2z-6&& \text{ swap the left and right side of the equation } \\[1 em]-2z-6 &= 10&& \text{ move -6 to the right } \\[1 em]-2z &= 10+6&& \\[1 em]-2z &= 16&& \text{ divide both sides by $ -2 $ } \\[1 em]z &= -\frac{16}{2}&& \\[1 em]z &= -8&& \\[1 em] \end{aligned} $$

This page was created using