Basic College Mathematics (9th Edition)

a. We are given the equation $-10x=40$. We would divide both sides by -10, because this would simplify the left side to $\frac{-10x}{-10}=x$. Doing so would allow us to isolate the variable on one side. b. We are given the equation $-25=5z$. We would divide both sides by z, because this would simplify the right side to $\frac{5z}{5}=z$. Doing so would allow us to isolate the variable on one side.