Beautiful! $$\vec{v}_{AC} = 1000 \hat \imath$$, $$\vec{v}_{CB} = 50 \hat \jmath$$. $$\vec{v}_{AB} = \vec{v}_{AC} + \vec{v}_{CB}$$. From this, we get $$\vec{AB} = 1000 \hat{i} + 50 \hat{j}$$