Constant forces $\vec{P}= 2\hat{i} - 5\hat{j} + 6\hat{k}$ and $\vec{Q}= -\hat{i} + 2\hat{j}- \hat{k}$  act on a particle. The work done when the particle is displaced from A whose position vector is $4\hat{i} - 3\hat{j} - 2\hat{k}$, to B whose position vector is $6\hat{i} + \hat{j} - 3k\hat{k}$ , is: