Question 27843
In order to type it into your graphing calculator, you usually have to solve the equation for y.
{{{4x+5y=80}}}subtract 4x from both sides:
{{{5y=-4x+80}}}divide by 5.
{{{y=-4x/5+16}}}

Now you can key y=-4x/5+16 into you graphing calculator and get:
{{{graph(300,400,-5, 25, -5, 20,
-4x/5+16
)}}}