Steemit : Help me any other understanding calculation

i am new to #steemit and i had earned a little .. but i didn't understand the calculation of the amount credited in my steemit wallet .

here is my post

http://i.imgur.com/SlgjUlZ.png

now see . my post beauty of darkness has earned 2.47 dollars

now what my wallet shows
http://i.imgur.com/hCaAW6k.png

Can anybody explain this calculation . ?
i hope my question is clear ...

thank you ..