Tanvi is a kickboxing instructor who will be teaching classes at a local gym. To get certified as an instructor, she spent a total of $80. Tanvi will be earning a base salary of $50 per month from the gym, plus an additional $15 for every class she teaches. If Tanvi teaches a certain number of classes during her first month as an instructor, she will earn back the amount she spent on certification. How much will Tanvi's expenses and earnings be?