Archie's dad is four years older than twice Archie's current age. If the sum of their ages is 52, how old is Archie,

D= 4 + 2A      given

D+A=52   or    52 - A = D      Sub THIS value of D into the first equation , then solve for 'A' (Archie's age)    the Dad = 52 - A

Archie is 16 years old. I think