You can put this solution on YOUR website! 10years+30years=40years.
8months+9months=17months
There are 12 months in a year, and as such, 17 months = 1 year and 17-12 months = 1 year and 5 months. You add this to the previous number.
40 years + 1 year + 5 months = 41 years and 5 months old.