A man bought 25 bottles of milk for 30c per bottle. He diluted the milk by adding 1 bottle of (free) water, and then he sold all 26 bottles of the resulting mixture for 40c per bottle. What percent of the man's profit on the sale of these 26 bottles was attributable to the water, not the milk?

I found that he gets a profit of 40*26-30*25=290 cents, but I dont know how to get the amount from the water.