1)

x+3 = 7

x = 4

since there is no y in this equation it means it takes all the values.. so points can be (4,0) , (4,1) , (4,2) , (4,-1) (4,-2).. etc

you'll get a vertical line.

by the way, this is not a graph.

2)

y + x = -4

y = -x -4

if x = 0 then y will be -4 and you'll get a point (0-4)

if x = 1 then y will be -5 and you'll get a point (1,-5)

now you just draw a line through these two points.

3)

x = y+2

y = x -2

if x = 0, y = -2, point (0,-2)

if x = 1, y = -1, point (1,-1)

again, draw a line through both points