Question 1019653
Hi there,
a father in now 38 years older than his son
F = 38 + S..........(1)
ten years ago he was twice as older as his son 
F - 10 = 2(S - 10)........(2)
Replace F in Eq(2) with 38 + S from Eq (1)
38 + S - 10 = 2(S - 10)
38 + S - 10 = 2S - 20
Collect like terms
38 - 10 + 20 = 2S - S
48 = S
Son is 48 years old 
Father is 86 years old.
Hope this helps :-)