Hallway Electric Fixture on Tenant 's Electric

[Mike Savage]

Hi, 

My tenant just discovered that three different ceiling lights with led bulbs in hallway are on her electricity. I do not have anything in lease that says anything exactly on who pays for the hallway lights. She is asking me to pay her for all the past months she has had lease with me. 

I checked online and it seems like Led bulbs have a consumption of $9 per year. With 3 bulbs in total, it will be 27$ per year. But she is demanding 70$ per month and not budging. What do you guys think I should do - pay her the entire amount or .. 

Thanks for a great forum and advice in advance. 

Mike.