Mechanical advantage (MA) is the ratio of the output force (resistance overcome) to the input force (effort applied). In other words, it is the amount of force gained by using a mechanical device, such as a lever or pulley system.

In this case, the effort force is 20 units and the resistance is 5 units. To calculate the mechanical advantage, we divide the resistance by the effort force:

MA = Resistance / Effort force

MA = 5 / 20

MA = 0.25

Therefore, the mechanical advantage is 0.25. This means that for every 1 unit of effort force applied, a resistance of 0.25 units can be overcome.