Let x = age of first client now. Then 39 - x = age of second client now
In 3 years, age of first client = x + 3 and age of second = 42 - x
Since x + 3 = 4(42 - x), we have 5x = 165.
So, x = 33 and 39 - x = 6
The first client is 33 years old and the second is 6 years old.