Final answer:
To find the sum of two vectors, place them tip to tail and draw an arrow from the tail of the first vector to the head of the second vector.
Step-by-step explanation:
The sum of two vectors can be found by placing them tip to tail and drawing an arrow from the tail of the first vector to the head of the second vector.
The dotted red vector that is most likely the sum of the two blue vectors is the one that completes the triangle formed by the two blue vectors.