Electricity wasn't the only energy cost. also look at logs for fire. being that they were bought for fire it is using heat energy. there for making the total energy cost the highest. only look at what is energy cost toward the overall bill.
If a single board measures 1/12 of a meter then it would take 12 boards to make a meter. Since, the stack is 2 meters high. You would multiply 12 and 2 to get 24. There is 24 boards in the stack.
The simplified form is 6x-6
Use photomath it will help you out fr