Answer
$158N$
Work Step by Step
We can find the required force as
$F_{spring}=K\Delta x$
$\implies F_{spring}=500(3.354-3)=177N$
We know that
$\Sigma F_x=0$
$\implies -F+2F_{spring} cos(63.4)=0$
$\implies -F+2(177N) cos(63.4)=0$
This simplifies to:
$F=158N$
