It's a linear function. We need only two points to the plotting of the graph.
[tex]3x+5y=-15\qquad\text{subtract 3x from both sides}\\\\5y=-3x-15\qquad\text{divide both sides by 5}\\\\y=-\dfrac{3}{5}x-3\\\\for\ x=0\to y=-\dfrac{3}{5}(0)-3=0-3=-3\to(0,\ -3)\\\\for\ x=-5\to y=-\dfrac{3}{5}(-5)-3=-3+3=0\to(-5,\ 0)[/tex]
