the slope is m = -5
and the two points are (x,3) & (5,-7)
now
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]put the values,
[tex]\begin{gathered} -5=\frac{-7-3}{5-x} \\ 5-x=\frac{-10}{-5} \\ 5-x=2 \\ x=5-2 \\ x=3 \end{gathered}[/tex]so the missing coordinate is at x =3
(3, 3)
