Answer:
 y = -x - 6 
Explanation:
If it's parallel, then it means that the slope will remain the same. The slope is 
-1. 
To find the y-intercept, you need to plug the coordinates into the equation, 
y = -1x + b
-3 = -1(-3) + b
-3 = 3 +b
-6 = b
The equation is y = -x - 6