Final answer:
The energy efficiency of the system is determined by dividing the energy output (25 units) by the energy input (100 units) and then multiplying the result by 100 to get a percentage, resulting in an energy efficiency of 25%.
Step-by-step explanation:
Energy efficiency is a measurement of how well a system converts energy into useful work and is calculated by taking the ratio of useful energy output to total energy input. In the given question, the formula to calculate efficiency is simply the energy output (25 units) divided by the energy input (100 units). To express this efficiency as a percentage, you multiply the ratio by 100. Therefore, the energy efficiency of the system is:
Efficiency = (Energy Output / Energy Input) x 100%
Efficiency = (25 units / 100 units) x 100%
Efficiency = 0.25 x 100%
Efficiency = 25%
Thus, the energy efficiency of the system is 25 percent.