Example 2: Solve
  x + y = 6
  y = x

Equations in slope-intercept form appear below.

    x + y = 6 becomes y = 6 - x
            slope = -1   
            y-intercept = 6

    y = x is already in slope-intercept form
            slope = 1
            y-intercept = 0

The graph appears like that below:

 

 

When we check our answer we get the work below.

x + y = 6

x = 3 and y = 3

(3) + (3) = 6

6 = 6

True

y = x

x = 3 and y = 3

3 = 3

True

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