The sum of angles of a triangle is 180°, so m∠K = 180° -45° -30° = 105°.
The Law of Sines tells you
... FL/sin(∠K) = FK/sin(∠L)
Solving for FL, we get
... FL = FK·sin(∠K)/sin(∠L)
... FL = a·sin(105°)/sin(30°) = a·sin(105°)/(1/2)
... FL = 2a·sin(105°) ≈ 1.93185a