To solve this question we have to make deduct these 2 years. 2117 minus 1977 will give the answer.
You are 140 years old.
(1680 months are passed.)
From 1977 to 2117 there are 140 years. If you want to learn your age in 2117 (born in 1977) your age is 140.
Let's see what will be your age if you born +1 or -1 from that date.