Asale on dog food that costs $10 a bag says buy 1 get one half off what is the percent discount on the dog food

If you have to pay full price for the first bag then there is no discount off the first bag purchased for 10 dollars.  If you get 50% off on the second bag then the second bag will cost you five dollars.  So that mean you would have to pay 15 dollars for both bags instead of 20 dollars.  So your discount on the entire purchase of two bags would be 25% of that purchase.