To solve this question we have to make deduct these 2 years. 2115 minus 1977 will give the answer.
You are 138 years old.
(1656 months are passed.)
From 1977 to 2115 there are 138 years. If you want to learn your age in 2115 (born in 1977) your age is 138.
Let's see what will be your age if you born +1 or -1 from that date.