Can anybody help me with this little problem ?

[Konfucius]

Peterson is now twice as old as his son was at that time Peterseon was
as old as his son is now.
Together, Peterson and his son are now 133 years old.
How old is the son ?

[Yuvraj Sujan]

Here is the answer :
Peter is 76 years old and his son is 57 years old.

Solution

Let P be the current age of Peter & S be the current age of his Son.
From the problem
P + S = 133 ------------ <1>

Let X years ago, Peter be of the same age as his son is now, so,

P - X = S -----------------<2>

Also from the problem

P = 2*( S - X) ------------<3>

Rearranging <2>
P = S + X ----------------<4>

Equating <3> and <4>

S + X = 2*(S-X)
=> 3*X = S
=> X = S/3

Putting this X in <3>
P = 2*( S-S/3)

P = 4*S/3 ---------------<5>

Replacing P from <5> in 1<>

4*S/3 + S = 133
7*S/3 = 133

S = 57

From <1> Again
P = 76.

Peace,
Sujan