Solution: As shown in the figure, in △ACO, it is known that ∠ Cao = 30 and the moment arm F is L = LOC =12loa =12× 80 cm = 40 cm;

LOB=LOA-LAB=80cm-20cm=60cm，G=30N，

FL = GLOB，

∴F=GLOBL=30N×60cm40cm=？ 45N。

So the answer is: 40, 45.