Answer
$F=20\sqrt3i+20j.$
Work Step by Step
If a vector $v=ai+bj$ makes an angle of $\alpha$ with the positive x-axis and has magnitude $||v||=\sqrt{a^2+b^2}$, then $a=||v||cos\alpha$ and $v=||v||sin\alpha$.
Hence here $F_i=||v||cos\alpha=40cos30^\circ=20\sqrt3$, $F_i=||v||cos\alpha=40sin30^\circ=20.$ Therefore $F=20\sqrt3i+20j.$