$$ \begin{aligned} -1 &= -1-6y&& \text{ swap the left and right side of the equation } \\[1 em]-1-6y &= -1&& \text{ move -1 to the right } \\[1 em]-6y &= -1+1&& \\[1 em]-6y &= 0&& \text{ divide both sides by $ -6 $ } \\[1 em]y &= \frac{0}{-6}&& \\[1 em]y &= 0&& \\[1 em] \end{aligned} $$