Question 688880
X+y=7
y=-x+7
set y=0 & solve for x
0=-x+7
-x=-7 
x=7 ans.
set x=0 & solve for y
y=-0+7
y=7 ans. 
 {{{ graph( 300, 200, -6, 10, -10, 10, -x +7) }}} (graph 300x200 pixels, x from -6 to 10, y from -10 to 10, -x +7).