Answer:

Step-by-step explanation:
The equation
is a <em>linear equation</em>. By definition, the independent term on this equation (that is, the number that is not being multiplied by
) is the <em>y-intercept</em>, which is a fancy way of saying "the point where the line crosses the y-axis".
By looking at the equation, we know that our y-intercept is <em>c. </em>By looking at the graph, we can see that the y-intercept is -3. Therefore,
and we get the complete version of our linear equation:

Now, looking at the graph we can see that the point
lies on the line of the equation, which means that the point is a solution to our equation. All we have to do is replace
and
by the values of the given point (which are
and
, respectively), and then solve for
:

And we are done!