The ages of 3 men are in ration 3,4,5 if the difference between the oldest and youngest is 18 yes find the sum of ages

The oldest age is $5x$.
The youngest age is $3x$.

The difference between the oldest and youngest age is 18 years.

First man's age: $3x = 3 \times 9 = 27$ years
Second man's age: $4x = 4 \times 9 = 36$ years
Third man's age: $5x = 5 \times 9 = 45$ years

Sum of ages $= 27 + 36 + 45$
Sum of ages $= 63 + 45$
Sum of ages $= 108$ years

The sum of their ages is $108 \text{ years}$.