Answer:
The son is five years old
Step-by-step explanation:
Let the son's age be x
A man is five as old as his son, 5x
In five years, he would be three times as old as his son
In five years: son would be x+5
Father 5x+5
3(x+5)=5x+5
3x+15=5x+5
Collect like terms
15-5=5x-3x
10=2x
Divide by 2
10/2=2x/2
x=5
The son is five years old