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Here is an approximate solution.
Your pulley system has a mechanical advantage of 2 ( assuming that the pulley attached to the top of the lever arm is a jam cleat to take up the slack and does not move). Since the pulley is not pulling at a 90 degree angle to the lever arm, its pull is the total pulley system pull times the sin of angle C. That angle appears to be about 60 degrees ( the sin of 60 degrees is .81 so you only get 81 percent of the pull). With the pulley system attached to two different positions on the lever arm, the effective attachment point is somewhere between the two. Assuming that the attachment point is midway is a close approximation.
The mechanical advantage of your lever arm is (A + B) / A
So the mechanical advantage of the whole press is (2 x sin C)x(A + B)/A.
So here is a guess at the dimensions and the answer.
A=10 cm, B=28 cm, C= 60 degrees
2 x .81 x 38 / 10 =6.1
With a mechanical advantage of 6.1, 10 kg hung on the pulley would give you 61 kg pressing weight.