The graph of the equation 2x + y = -3 is a straigth line.
the formula is;
where 'm' is the slope
'b' is the y intercept.
To graph of this equation you can also trial and error.Assign the vaue of either X or Y by Zero .Say,
y=-2x-3 ------that is the equation above.Im just only into the form above.
Therefore the coordinates are:
(-3/2,0) & (0,-3)
Then, plot on the Cartesian plane.
Hope it helps.:)