I am a self-learner using textbooks. For example, I am using Spivak Calculus. I am working out a textbook problem in my notebook or I am writing down the intricacies of the proofs in the notebook. I have the Camscanner Android app in my mobile. I take photos of my working-out and edit it using Cam-scanner app. I post it over here for verification. Is my action within the rules of PF? Is posting pictures within the rules?