Fish Price, Brain Challenge

Today Briquinex sends you to the market to buy some fish. There you see a big fish. You ask the seller how much it costs? He answers you:

- The price of the body is equal to the head and tail taken together.
You ask, but how much cost head and tail? He answers :
- The head costs 20 dollars and tail same as the head and half body.
Your are required to determined how much the fish costs?

photo source:wikipedia