Answer
To do the least amount of work, we should pull the crate with the force at an angle of $30^{\circ}$
Work Step by Step
The work that we do on the crate is $F~d~cos~\theta$, where:
$F$ is the force we apply
$d$ is the crate's displacement
$\theta$ is the angle between the force vector and the displacement vector
To decrease the work we do on the crate, we should apply the force at an angle. To do the least amount of work, we should pull the crate with the force at an angle of $30^{\circ}$
