Question

What ages, in years, does the interval of 80-89 months represent

Answer 1

Well, there are 12 months in a year, so divide 80 and 89 by 12, which gives you 6 years and a remainder of 8 months, and 7 years with a remainder of 5 months.  So your answer is 6 years 8 months- 7 years 5 months.