Step 1: Simplify the vector expression.
First, simplify the vector components:
\[
- (s + 4s) \hat{i} = -5s \hat{i}, \quad (7 - 2s) \hat{j}, \quad (3 + 4s) \hat{k}
\]
So, the vector is:
\[
\mathbf{V} = -5s \hat{i} + (7 - 2s) \hat{j} + (3 + 4s) \hat{k}
\]
Step 2: Find the magnitude of the vector.
The magnitude of the vector is given by:
\[
|\mathbf{V}| = \sqrt{(-5s)^2 + (7 - 2s)^2 + (3 + 4s)^2}
\]
Step 3: Calculate the unit vector.
The unit vector \(\hat{v}\) parallel to \(\mathbf{V}\) is obtained by dividing the vector by its magnitude:
\[
\hat{v} = \frac{\mathbf{V}}{|\mathbf{V}|}
\]