The slope of the line passing through the points (2, -1) and (x, 5) is -1. Find x?

Answer: Option B

$$\begin{array}{rl}& \text{Slope}\Rightarrow m=-1\\ & m=\frac{y_2-y_1}{x_2-x_1}\\ & -1=\frac{5-\left(-1\right)}{x-2}\\ & -1\left(x-2\right)=6\\ & -x+2=6\\ & x=2-6\\ & x=-4\end{array}$$