how do i graph x + y = 1

put y on one side y=-x+1

im doing an online test and its asking me to find the equation that matches the graph. But im not sure how to figure it out.

well the graph should have a negative slope with 1 as y-intercept look for a graph with those tips.

it goes from -1 then goes up one right one up one right one....so im guessing the equation is x+y=1...dude im not that good in math...i realy suck sometimes the other answers it gives me are:x – y = –1 ; x + y = –1 ; –x + y = –1