$$ \begin{aligned} 24 &= -x+14&& \text{ swap the left and right side of the equation } \\[1 em]-x+14 &= 24&& \text{ move 14 to the right } \\[1 em]-x &= 24-14&& \\[1 em]-x &= 10&& \text{switch signs on both sides} \\[1 em]x &= -10&& \\[1 em] \end{aligned} $$