Answer: 4 years old
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Work Shown:
- x = son's present age
- x+25 = father's present age being 25 years older than his son
Let's fast forward 19 years into the future to get these ages
- x+19 = son's future age
- (x+25)+19 = x+44 = father's future age
These future ages combine to 71, so,
(x+19) + (x+44) = 71
2x+53 = 71
2x = 71-53
2x = 8
x = 8/2
x = 4
The son is currently 4 years old, and his dad is currently x+25 = 4+25 = 29 years old.
Fast forward 19 years to the future and the son will be 4+19 = 23 years old and the father will be 29+19 = 48 years old. Their combined future ages is 23+48 = 71 which fully confirms the answer.