Pay sales tax with the Retail Sales Tax Return For Occasional Sales (DR 0100A) on the tangible personal property included in the purchase of the business by the 20th day of the month following the sale.
So, to avoid pregnancy she has to better avoid unprotected sexual intercourse in this period. The rest of the days i.e., starting from menstruation to the 10th day and again from 21st day up to menstruation are the safe days or the safe period to avoid pregnancy.
For you as a woman to know your Safe and Unsafe period you must first off all know your ovulation time base on the length of your menstrual cycle. By simple mathematic, Minus 14 from the total number of days of your menstrual cycle.