At what minimum distance r from the fulcrum can the force F1 = 20 N be applied to balance the force

At what minimum distance r from the fulcrum can the force F1 = 20 N be applied to balance the force F2 = 50 N acting on the lever and having a shoulder of 30 cm?

According to the balance rule of the lever:
F1 / F2 = r2 / r1, where F1 is the force acting on the shoulder r1 (F1 = 20 N); F2 is the force acting on the arm r2 (F2 = 50 N), r1 is the arm of the lever on which the force F1 (cm) acts, r2 is the arm of the lever on which the force F2 acts (r2 = 30 cm).
Let us express and calculate the length of the lever arm r1:
r1 = F2 * r2 / F1 = 50 * 30/20 = 75 cm.
Answer: A force equal to 20 N must be applied at a distance of 75 cm from the fulcrum.