Question 142112
Graph the inequality.
4x + 5y <_ 20 (of course the _ goes under the <) 
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1st: Graph the EQUALITY which is the boudary of the INEQUALITY.
y = (-4/5)x + 4
{{{graph(400,300,-10,10,-10,10,(-4/5)x+4)}}}
2nd: Shade the half-plane BELOW the line because your inequality
is LESS THAN.
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The line and the shaded area comprise the graph of your problem.
Cheers,
Stan H.