Given,
The line graph is passing through the points (3,835) and (8,560).
The slope of the line is calculated as:
[tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex]
Substituting the values of points then,
[tex]\begin{gathered} m=\frac{560-835}{8-3} \\ m=\frac{-275}{5} \\ m=-55 \end{gathered}[/tex]
Hence, the slope of line is -55 and the balance decreased by $55 per month.
