Let Alex (the youngest) be n
Sam is n+3 because he is three years older
George is n+5 because he is 2 years older than Sam (n+3 +2) = n +5
All their ages summed = 35
So
n + n +3 + n + 5 = 35
Combine like terms
3n + 8 = 35
- 8 -8 subtract 8 from both sides of the equation
3n = 27
3 3 divide both sides by 3 and get n= 9
So Alex is 9
Sam is 12 since he is 3 years older than Akex
George is 14 since he is 2 years older than Sam
9 + 12 + 14 = 35