1. The problem asks for the slope of the line given by the equation $$15x + 3y = 45$$. 2. To find the slope, we need to rewrite the equation in slope-intercept form $$y = mx + b$$, where $$m$$ is the slope. 3. Start by isolating $$y$$: $$15x + 3y = 45$$ Subtract $$15x$$ from both sides: $$\cancel{15x} + 3y - \cancel{15x} = 45 - 15x$$ which simplifies to $$3y = 45 - 15x$$ 4. Now divide both sides by 3 to solve for $$y$$: $$\frac{3y}{\cancel{3}} = \frac{45 - 15x}{\cancel{3}}$$ which simplifies to $$y = 15 - 5x$$ 5. Rewrite the equation as $$y = -5x + 15$$ 6. From the slope-intercept form $$y = mx + b$$, the slope $$m$$ is the coefficient of $$x$$. 7. Therefore, the slope of the line is $$\boxed{-5}$$.