Brother agrees to help step-sister with math in exchange for incest

The girl went to university, but she was very stupid and didn't want to study. Then she decided to pester her stepbrother to do her difficult homework for her. At first, the dude rebuffed her, but then he saw an advantage for himself and made a condition that he would help the girl in exchange for sex. The bitch knew how to do it well, so she made the guy happy with hard incest and got not only benefits, but also pleasure herself.