The age of father is 3 years more then 3 times the son's age. 3 years hence the, age of father will be 10 years more than twice the age of son. Find their present ages.

Let father’s age be x & son’s age be y

By 1st condition:

3 + 3y = x (three plus three times age of son is father’s age)

By 2nd condition:

x + 3 = 2(y + 3) + 10 [here we are talking about 3 years hence. So 3 has to be added to their present ages, and then satisfy the condition]

So the final 2 equations are

x-3y = 3 … (1)

x-2y = 13 … (2)

(1) - (2)
-y=-10
y=10
sub y=10 in (1)
x-(3*10)=3
x-30=3
x=3+30
x=33

Solving them we get

y = 10, x = 33

So the father’s present age is 33 and that of the son is 10.