Answer:
15%
Step-by-step explanation:
Step one:
Given data
Energy source= 300J
Useful energy = 45J
Waste energy = 255J
Required
The efficiency of the solar system
Step two:
The efficiency is computed by factoring only the useful work and the energy source
Efficiency= 45/300*100
Efficiency= 0.15*100
Efficiency= 15%