Read The Student I’m Tutoring is in Heat – Please Don’t Tease Sensei’s Kurikuri Manga:
Minako Nishiwaki's life is a constant struggle for money since her mother is addicted to gambling and regularly incurs large amounts of debt. To pay off the latest debt, Minako accepts a position as a live-in tutor to Naoki, the rebellious son of a rich family. He is in his last year of high school and has terrible grades, but more.. if she can successfully get him into university, the family will pay her enough to take care of the debt.
However, it seems Naoki requires some... special motivation.