First we need to find the slope. We can find the slope by [tex]\frac{rise}{run}[/tex]. The slope is [tex]\frac{-5}{4}[/tex]. You can also find the slope by calculating the change in the y values over the change in the x values. If the line looks like /, it has a positive slope, if it looks like \, it has a negative slope.
The slope intercept form is [tex]y=mx+b[/tex]
Where [tex]m[/tex] is slope and [tex]b[/tex] is the y-intercept.
To find the y-intercept is (0,16.25) because we take the last [tex]y[/tex] value we know, 15, and add [tex]\frac{5/4}[/tex] (|m|). So now we just put it all into the equation.
[tex]y=\frac{-5}{4}x+16.25[/tex]
