Question 300394
The quickest way to graph is to find the intercepts and plot them.
To find the x-intercept, set y=0 and solve for x.
{{{8x+4y=20}}}
{{{8x+0=20}}}
{{{8x=20}}}
{{{x=5/2}}}
(5/2,0)
To find the y-intercept, set x=0 and solve for y.
{{{8x+4y=20}}}
{{{0+4y=20}}}
{{{4y=20}}}
{{{y=5}}}
(0,5)
.
.
.
{{{drawing(300,300,-2,6,-2,6,circle(0,5,.2),circle(5/2,0,.2),grid(1))}}}
.
.
.
Now connect the two points with a line extending it in both directions. 
{{{drawing(300,300,-2,6,-2,6,circle(0,5,.2),circle(5/2,0,.2),grid(1),graph(300,300,-2,6,-2,6,(20-8x)/4))}}}