To solve this question we have to make deduct these 2 years. 2115 minus 1975 will give the answer.
You are 140 years old.
(1680 months are passed.)
From 1975 to 2115 there are 140 years. If you want to learn your age in 2115 (born in 1975) your age is 140.
Let's see what will be your age if you born +1 or -1 from that date.