Answer:
Present age
Son: 15
Father: 45
Step-by-step explanation:
Remark
Thank you for the translation. Without it, the problem would be impossible -- at least for me.
Givens
Let the present age of the father = x
Let the present age of the son = y
Solution
x + y = 60
How many years will pass? You could say it's z.
x + z = y                          When z years pass, the son will be his father's present age.
x + z + y + z = 120          when z is added to both their current ages, the result is 120                   Collect like terms
         
x + y + 2z = 120             
<u>x + y         = 60  </u>            Subtract The very first equation
2z = 60                          Divide by 2
z = 60/2                         30 years have passed.
z = 30
x + z = y
x + 30 = y                       Substitute x + 30 for the present y value (the father).
x + x + 30 = 60
2x = 30
x = 15
x + y = 60
15 + y = 60
y = 60 - 15
y = 45
So the son's age right now is 15
The father's age right now is 45