Let the age of the middle bother be x.
The oldest brother is 1 year older than the middle brother,so his age is x + 1.
The youngest brother is 1 year younger than the middle bother, so his age
is x - 1.
Add the three ages and get 63.
x - 1 + x + x + 1 = 63
3x = 63
x = 21
Answer: The age of the middle brother is 21.