Question 294464

Fastest way is to find the intercepts. 
To find the x-intercept, set y=0 and solve for x.
{{{4x+5y=20}}}
{{{4x+5(0)=20}}}
{{{4x=20}}}
{{{x=5}}}
(5,0)
To find the y-intercept, set x=0 and solve for y.
{{{4x+5y=20}}}
{{{4(0)+5y=20}}}
{{{5y=20}}}
{{{y=4}}}
(0,4)
Plot those two points and connect them.
{{{drawing( 300, 300, -6, 6, -6, 6,grid( 1 ),circle( 5, 0, .2 ),circle( 0, 4, .2 ),
graph( 300, 300, -6, 6, -6, 6, (20-4x)/5) 
)}}}