Hello!
The answer is:
The last equation,

Why?
To find which of the given equations represents a line that passes through the point (-9,-3) and has a slope of -6, we need to find an equation that can be satisfied by evaluating the given point.
We can see that the only equation that can be satisfied evaluating the point (-9,-3) is the last equation:

Evaluating the point, we have:



We can see that the equation is satisfied!
Also, we can see that evaluating the point into the other equations, they will not be satisfied.
Let's prove that:
Evaluating:
First equation:

The equation is not satisfied.
Second equation:

The equation is not satisfied.
Third equation:



The equation is not satisfied.
Hence, the correct option is the last option, the equation that represents a line that passes through (–9, –3) and has a slope of –6 is the last equation:

Have a nice day!
Note: I have attached a picture for better understanding.