A particle acted on by constant forces $4\hat i+\hat j-3\hat k$ and $3\hat i+\hat j-\hat k$ is displaced from the point $\hat i + 2\hat j + 3\hat k$ to the point $5\hat i +4\hat j+\hat k$. The total work done by the forces, is

40 units

We have,

$\vec F$ = Total force = $7\hat i+2\hat j-4\hat k$

$\vec d$ = Displacement vector = $4\hat i +2\hat j-2\hat k$

∴ Work done = $\vec F.\vec d=(28+ 4+8)$ units = 40 units.