We have to find the slope of the following equation

$$x+5y=9$$

$$5y=-x+9$$

$$y=-\frac{1}{5}x+\frac{9}{5}.............(1)$$

We know that the equation of slope is

$$y=mx+c................(2)$$

where,

$$m=\frac{a}{b}$$

So comparing equation (1) with (2), we have

$$slope=m=-\frac{1}{5}$$