Given that the required linepasses through the points (15, 5)and (5, 15).
Find the slope of the line using teo-point formula.
[tex]\begin{gathered} m=\frac{y_2-y_1}{x_2-x_1} \\ =\frac{15-5}{5-15} \\ =\frac{10}{-10} \\ =-1 \end{gathered}[/tex]Substitute the value of m into theslope-intercept form y = mx+c.
[tex]y=-x+c[/tex]Plug in the point (5, 15)to find c, the y-intercept.
[tex]\begin{gathered} 15=-5+c \\ c=20 \end{gathered}[/tex]Thus, y = -x + 20, which is the required equation of line.
