The final equation is:

Further explanation:
The general form of equation of a line in slope-intercept form is:

Here m is the slope
Given
m=1
(x,y) = (-7,-4)

To find the value of b, we have to put the point in the equation

The final equation is:

Keywords: Slope-intercept form, equation of line
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Answer:
x=9
Step-by-step explanation:
Using elimination method.
Add equation 1 to equation 2
x + y = 11
x - y = 7
---------------
2x + 0 = 18
Divide both sides by 2
2x = 18
---- ----
2 2
x = 9