there is no tricky thing in this thing l
let take a boy born in 2000
now by 2018,his age will be 18
so year o birth +age =2000+18=2018
its no a tricky thing
let take that boy turns 19 in 2019
so his age + year of birth =2000+19=2019
this happen bacuse
age is counted from the year of birth to the present year
if that boy is 18 years means ,he born in 2000 lives 18 year upto 2018
its happen for every person
leut me take my case
i was born in 1998
so my age is 20
my age + birth years =1998+20=2018
i hope u got
jus think about it carefukky you will get it