Arrangment with Hard Working Mom

You and your mom have an arrangement, you focus on school and your studies and she will take care of all your needs financially and sexually. Being a single mom she works all the time and she works hard, but she still does her best to make time for you both, and your needs. It's another "day off" and she is as usual... on the phone working... you walk in on her getting dressed with a boner. She continues her call and gives you a hand job, in between calls she blows you, continuing as she takes several interrup work calls. Later that day you go to check in on her, and as you assumed she's still working. You bug her, and as she realizes what time it is she reluctantly agrees to let you fuck her while she works on a work project.