How Old Are They Now?

[nycmath]

Pat is 20 years older than his son James. In two years Pat will be twice as old as James. How old are they now?

[Eigenvalue]

Let P be Pat's age and J be James' age.
P=20+J
P+2=2(J+2)
P=2J+2

Set 2J+2 and 20+J equal, as they equal to P
2J+2=20+J
J=18
P=38

James is 18 years old and Pat is 38 years old