To solve this question we have to make deduct these 2 years. 2004 minus 1999 will give the answer.
You are 5 years old.
(60 months are passed.)
From 1999 to 2004 there are 5 years. If you want to learn your age in 2004 (born in 1999) your age is 5.
Let's see what will be your age if you born +1 or -1 from that date.