What is the sum of the two vectors (2,-1) and (3,3)?

(5, 2)

We simply add up the corresponding coordinates. The x coordinates of the two vectors are 2 and 3. They add to 2+3 = 5

The y coordinates are -1 and 3. They add to -1+3 = 2

So overall, 
(2,-1) + (3,3) = (2+3, -1+3) = (5,2)
is the answer