The answer is 9 because 5*(-3)+8+9-(-7)=9
We can observe that the function describing the graph is linear and so the equation is of linear nature:

Numbers m and n have special names. m is called the slope, n is called y-intercept.
From the graph one can tell that the line intercepts y-axis at y = -1 that means n = -1. What about the slope you say?
The slope can be calculated using two points' coordinates that lie on the line:

Now our line has an equation,

Hope this helps.
I, sorry but that problem does not make any sense how do 5x-6 tell me?
Answer:
x= 4 1/6, -3 1/6
Step-by-step explanation:
Hope this helps