Explanation:

Let one year ago
Sam’s age be 4X years
And, Ash’s age be 3X years
Present age of Sam = (4X + 1) years
Present age of Ash= (3X + 1) years
One year hence
Sam’s age = (4X + 2) years
Ash’s age = (3X + 2) years
According to question,
[4X + 2] divide by [3X + 2] = 5 / 4
16X + 8 = 15X + 10
or, X = 2
Sum of their present ages = 4X + 1 + 3X + 1
= 7X + 2
= 7 x 2 + 2 = 16 years.