A father is 4 times older than his son in 20 years he will be twice as old what age are they now?

Let, son's age be 'x'.

So, Father's present age is 4x.

Now, by the question, after 20 years, fathers, age=4x+20 and son's age =x+20 and,

twice son,s age= father's age so,

2(x+20)=4x+20

2x+40=4x+20

2x=20

x=10

So, son's age is 10 years and father's age is 4x or 40 years.