Let E be the total amount of energy that the heating system would consume in order to transform 9000kWh into useful thermal energy.
Since the efficiency of the system is 45%, then, 9000kWh is equal to 45% of E.
This means that 45% of the total energy consumed is transformed into useful thermal energy. Then:
![(E)/(100)=(9000kWh)/(45)](https://img.qammunity.org/2023/formulas/physics/college/4ay2obxg44qgoyprp5zw19picyjlo17yct.png)
Solve for E:
![E=(100)/(45)*9000kWh=20,000kWh](https://img.qammunity.org/2023/formulas/physics/college/nar0muxwccdzzgrkrnjb4nhu7vqsduxs7c.png)
Therefore, the total amount of energy consumed by the system would be 20,000kWh.