A father is 26 years older than his son. In 3 years time, the son’s age will be one third his father’s age. What is the present age of the son?

Let son’s age = x years

Father’s age =$(x+26)$  years

After “3” years,

Son’s age $=(x+3)$  years

Father’s age $=(x+26+3)$

$=(x+29)$ years

As per problem, $(x+3)=\frac{1}{3}(x+29)$

$3x+9=x+29$

$2x=20$

$x=10$

Son’s age = 10 years