You get the answer by inserting values in slope formula and then solving for k. I'll call k, y_2
[tex]
s=\dfrac{y_2- y_1}{x_2-x_1}\Rightarrow2=\dfrac{y_2-3}{5-1} \\
2=\dfrac{y_2-3}{4} \\
8=y_2-3\Rightarrow y_2=11
[/tex]
So the answer k = -5 is incorrect because k = 11.
Hope this helps.
