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4x+5y<=20  OR y <= (-4/5)x + 4  Slope m = (-4/5) and y-intercept Pt(0,4)
I. Graph line:  Plot y-intercept and find at least one more PT using the slope
Note: as y increases/decreases by 4, x increases/decreases by 5 in opposite direction

II. Shade portion represented by the inequality: 
In this example: below and including the line