Determine how much weight can be lifted using a movable block, the weight of which is 18 N

Determine how much weight can be lifted using a movable block, the weight of which is 18 N, applying a force of 210 N to the free end of the rope.

Given:
P = 18 Newton – weight of the movable block;
F = 210 Newtons – the force applied to lift a load using a movable block.
It is required to determine m (kilogram) – the mass of a load that can be lifted using a block, applying a force equal to 210 Newtons to it.
We will assume that the load is lifted evenly.
Then, since the movable block gives a 2-fold gain in strength, we find the mass of the load from the following formula:
2 * F = F gravity + P;
2 * F = m * g + P, where g = 10 Newton / kilogram (approximate value);
m * g = 2 * F – P;
m = (2 * F – P) / g = (2 * 210 – 18) / 10 = (420 – 18) / 10 = 402/10 = 40.2 kilograms.
Answer: applying a force of 210 Newtons, on this block, you can lift a load weighing 40.2 kilograms.