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.
shortest cycle=27 days. longest cycle=28 days. Subtract 18 days from the shortest cycle 27-18=9 days. Subtract 10 days from the longest cycle 28-10=18 days. The 9th day to 18 th day from your last period is the unsafe period. The rest is the safe period.