5x - 8y = 40

1.  Make a table of arbitrary values:

 x |   y   
 4 | 
 2 | 
-2 | 
-4 | 
 Calculate the other variable values:



Fill in the table:

 x |   y   
 4 | -2.5
 2 | -3.75
-2 | -6.25
-4 | -7.5

Plot the points:



Draw a line through them:





2.  Get the equation in slope-intercept form y = mx+b

  5x - 8y = 40
      -8y = -5x + 40
        y = x - 5

The slope is  and the y-intercept is (0,-5)

Start at the y-intercept, draw a vertical line upward
5 units (the numerator of the slope), and from there
draw a horizontal line rightward 8 units (the denominator
of the slope):



Draw a line through the y-intercept (0,-5) and the end of the vertical
line:




3.  Find the two intercepts

To find the x-intercept, we substitute 0 for y:

  5x - 8y = 40
5x - 8(0) = 40
  5x - 0  = 40
       5x = 40
        x = 8, so the x-intercept is (8,0)

To find the y-intercept, we substitute 0 for x:

  5x - 8y = 40
5(0) - 8y = 40
   0 - 8y = 40
      -8y = 40
        y = -5, so the y-intercept is (0,-5).

Plot the intercepts:



Draw a line through those two intercepts:



Edwin