Let F be a force acting at the point of application, let the point of application P to move to Q. Then the work done W.L. by the force F in moving the point of w.r.t. to Q is

The force vector is given as:

The student's work shows the calculation for work done as $35 + 4 + 3 = 42$.
The formula for work done by a constant force $\vec{F}$ causing a displacement $\vec{d}$ is $W = \vec{F} \cdot \vec{d}$.
If we assume the displacement vector $\vec{d}$ is such that its components, when multiplied by the corresponding components of $\vec{F}$, yield these values, we can deduce $\vec{d}$.
Let $\vec{d} = (d_x \hat{i} + d_y \hat{j} + d_z \hat{k})$.
Then $\vec{F} \cdot \vec{d} = (7)(d_x) + (4)(d_y) + (-3)(d_z)$.
Comparing this with the student's calculation:
$7d_x = 35 \implies d_x = 5$
$4d_y = 4 \implies d_y = 1$
$-3d_z = 3 \implies d_z = -1$
So, the implied displacement vector is $\vec{d} = (5\hat{i} + 1\hat{j} - 1\hat{k})\, \text{m}$.

Using the force vector $\vec{F} = (7\hat{i} + 4\hat{j} - 3\hat{k})\, \text{N}$ and the implied displacement vector $\vec{d} = (5\hat{i} + 1\hat{j} - 1\hat{k})\, \text{m}$:

The work done is consistent with the student's calculation.

The final answer is $\text{42 J}$.