Question 857499
You need two points to plot a line. 
{{{x=0}}}
{{{y=-2(0)+5=5}}}
Plot (0,5).
{{{drawing(300,300,-10,10,-10,10,grid(1),circle(0,5,0.3))}}}
Now choose any other point.
How about {{{x=2}}}
{{{y=-2(2)+5=-4+5=1}}}
Plot (2,1).
{{{drawing(300,300,-10,10,-10,10,grid(1),circle(0,5,0.3),circle(2,1,0.3))}}}
Now draw the line through both of those points.
{{{drawing(300,300,-10,10,-10,10,grid(1),circle(0,5,0.3),circle(2,1,0.3),graph(300,300,-10,10,-10,10,-2x+5))}}}