Explanation
Step 1
when you have 2 points of a line P1 and P2, you can easily find the slope using:
[tex]\begin{gathered} \text{slope}=m=\frac{y_2-y_1}{x_2-x_1} \\ \text{where} \\ P1(x_1,y_1) \\ P2(x_2,y_2) \end{gathered}[/tex]Let
P1=A=(-1,5)
P2=B=(3,-1)
Step 2
replace
[tex]\begin{gathered} \text{slope}=m=\frac{y_2-y_1}{x_2-x_1} \\ \text{slope}=m=\frac{-1-5}{3-(-1)}=\frac{-6}{3+1}=\frac{-6}{4}=-\frac{3}{2} \end{gathered}[/tex]I hope this helps you