In case u r true to ur username and in this case the books are HS course related, go to ur dad.
Tell him u can't concentrate on ur studies for her. U r unable to provide those extra efforts to ur own study. And ur problem will be solved.
Every dad is selfish enough about his son's study.
But, I still can't get ur problem. HS exam has started and u r not appearing for it, means u r in 11th. Then why don't u want to show her some maths work.
Better ask her to come twice a week (sat-sun afternoon). Phirbhi, why would u avoid?? Why...hmmm...