God told Hosea to have sex with an adulteress. So Hosea bought one. How much did he pay?

Fifteen pieces of silver and a homer and a half of barley

The LORD unto me, Go yet, love a woman beloved of her friend, yet an adulteress.... So I bought her to me for fifteen pieces of silver, and for an homer of barley, and an half homer of barley. Hosea 3:1-2