Muniya was born on 5 March 2005. She got her first tooth on 15 September 2005.
We know that March is the third month of the year and September is the ninth month of the year.
Thus, Muniya was 6 months old till 5 September 2005. Now, there are 10 more days for 15 September 2005. Hence, Muniya was 6 months 10 days old when she got her first tooth. Six months have passed from March to September.