According to the meaning of the question, O is the fulcrum, A is the power point, and OA is the largest power arm. After point A, it is the vertical line of OA, and the direction is downward, as shown in the figure, and the F power is made.

According to the lever balance condition f? OA=G？ OB available: F=G? OBOA=G2=20N。

So the answer is: 20 N; The direction of f is shown in the figure.