Answer:Jeff is 26 years old
Erica is 25 years old
Alden is 24 years old
Explanation:
Let the age of Jeff be x years.
Let the age of Erica be y years.
Let the age of Alden be z years.
Jeff is one year older than Erica. This means that
x = y + 1
Erica is one year older than Alden. This means that
z = y - 1
If the sum of their ages is 75, it means that
x + y + z = 75 - - - - - - - - - - - - 1
Substituting x = y + 1 and z = y - 1 into equation 1, it becomes
y + 1 + y + y - 1 = 75
3y = 75
y = 75/3 = 25 years
x = y + 1 = 25 + 1
x = 26 years
z = y - 1 = 25 - 1
z = 24 years