Given the slope m=-0.5 and the point (x,y)=(1,3), we can find the equation of the line using the slope-point formula:
[tex]\begin{gathered} m=-0.5 \\ (x_0,y_0)=(1,3) \\ y-y_0=m(x-x_0) \\ \Rightarrow y-3=-0.5(x-1) \\ \Rightarrow y-3=-0.5x+0.5 \end{gathered}[/tex]To write it in the slope-intercept form, we solve for y:
[tex]\begin{gathered} y-3=-0.5x+0.5 \\ \Rightarrow y=-0.5x+0.5+3=-0.5x+3.5 \\ y=-0.5x+3.5 \end{gathered}[/tex]Therefore, the equation in slope-intercept form is y=0.5x+3.5