First, you have to convert it to slope intercept form, which is [tex]y=mx+b[/tex])
[tex]2x+y-2x=15-2x[/tex]
[tex]y=-2x+15[/tex]
Knowing this, you can easily find the slope. In slope intercept form, the "m" or the coefficient of "x," is the slope.
[tex]m=-2[/tex]
Therefore, your slope is -2.