Six vectors, $\vec{a}$ through $\vec{f}$ have the magnitudes and directions indicated in the figure. Which of the following statements is true?

According to the triangle law of vector addition, if two vectors are represented by two sides of a triangle taken in order, their resultant is represented by the third side taken in the opposite order.
In the provided diagram, vectors $\vec{d}$ and $\vec{e}$ are in order, and $\vec{f}$ completes the triangle in the opposite direction.


Therefore, $\vec{d}+\vec{e}=\vec{f}$.