Correct! $$\vec{A} = \hat{i} - \hat{j}$$, $$\vec{B} = - 2 \hat{i} + 3 \hat{j}$$ and $$\vec{C} = 2 \hat{i} + \hat{j}$$
So, $$3 \vec{A} = 3 \hat{i} - 3 \hat{j}$$, $$- 2\vec{B} = 4 \hat{i} - 6 \hat{j}$$ and $$4 \vec{C} = 8 \hat{i} + 4\hat{j}$$. We just have to add all these three vectors.
Up to now, we have talked about vectors abstractly. Let us now look at the use of vectors in Physics. Position is a vector. For example, if an object A is located at position P as shown, we can write its position vector as $$\vec{r}_A$$.