Let the present age of son = x

and the present age of father = y

Difference in their ages = y - x

Given, when the ages will be as old as father today their ages will add up to 126 years

=> {x + (y - x)} + {y + (y - x)} = 126

=> {x + y - x} + {y + y - x} = 126

=> y + 2y - x = 126

=> 3y - x = 126       .................1

Again, when the father as old as son is today, their ages add up to 38 years

=> {y + (x - y)} + {x + (x - y)} = 38

=> {y + x - y} + {x + x - y} = 38

=> x + 2x - y = 38

=> 3x - y = 38       .................2

Multiply by 3 in equation 2, we get

=> 9x - 3y = 114   ..............3

Add equation 1 and 3, we get

    8x = 240

=> x = 240/8

=> x = 30

From equation 1, we get

    3y - 30 = 126

=>3y = 126 + 30

=> 3y = 156

=> y = 156/3

=> y = 52

So, the present age of son = x = 30 years

and the present age of father = y = 52 years