For the line  $-3x-5y=15$

Given,  $5y=-3x-15$
using $y=mx+c,y=-\frac{3}{5}x-3$
Here the slope is negative, i.e., the line makes an angle greater than ${90}^o$ with the x-axis. As intercept is negative, it indicates that the line will cut the y-axis on its negative side
When  $x=0,y=-3$
When  $y=0,x=-5$
Method : Using  $\frac{x}{a}+\frac{y}{b}=1;$
 $\frac{-3x}{15}-\frac{5y}{15}=1\Rightarrow \frac{x}{(-5)}+\frac{y}{(-3)}=1$