The Clever Lady

Leena, a clever lady lived in a house along with his 2 children. One day, a lady beggar went to Leena's house. Leena, the clever lady asked the beggar how much she get a day. "10 rupees" the lady beggar replied.

Leena felt sorry and gave her a job with a salary of 16 rupees/day along with free food. Along with that, she put forward a condition too... The condition was that, If the beggar is in leave, she has to give 20 rupees/day to Leena.

Beggar accepted the condition and joined for work. After 36 days Leena checked the attendance register for payment, but there was no amount payable. If so, how many days she went for job in that 36 days?