Answer:
Carlos born in 1944
Julio born in 1945
Ricky born in 1946
Explanation:
x = Carlos age
x+1 = Julio age
x+2 = Ricky age
x + x+1 + x+2 = 129
3x + 3 = 129
3x = 126
x = 42 (Carlos age)
x+1 = 43 (Julio age)
x+2 = 44 (Ricky age)
1990 - 42 = 1944 (year Carlos born)
1990 - 43 = 1945 (year Julio born)
1990 - 44 = 1946 (year Ricky born)