It's really not clear what your question is. First, that is a "table", not a "graph" and you don't seem to have any trouble reading it. I think you are just asking about finding the difference between "7 years 2 months" and "6 years 6 months".

There are several different ways of doing this- it is really just like subtracting fractions. "7 years 2 months" is the same as "7 and 2/12 years" and "6 years 6 months" is the same as "6 and 6/12 years". Since the numerator "6" is larger than "2", you need toborrowfrom the "7": 1 year is 12 months or 12/12 years so "7 and 2/12 years" is the same as "6 and (12+2)/12= 6 and 14/12 years". 6- 6= 0 and 14- 6= 8 so this is a difference of "0 and 8/12 years" or "8 months".

Just as you could also subtract fractions by changing to an "improper" fraction, you can do that here: "7 and 2/12" is the same as (12(7)+ 2)/12= 86/12 and "6 and 6/12" is the same as (12(6)+ 6)/12= 78/12. 86/12- 78/12= 8/12 years or 8 months.

Without the fractions, that is the same as converting "years and months" to just "months". 7 years is 7(12)= 84 months so "7 years and 2 months" is 84+ 2= 86 months. 6 years is 6(12)= 72 months so "6 years and 6 months" is 72+ 6= 78 months. Again the difference is 86- 78= 8 months.