The sum of present ages of A and B is 48 years.  Today B is 4 years older than C.  The respective ratio of the present ages of A and C is 4 : 7.  What was B's age two years ago?

30

A + B = 48 years

ATQ,

⇒ B = C + 4

⇒ A + C + 4 = 48

⇒ A + C = 44 and

    A   :    C

    4   :    7    → 11R = 44 ⇒ 1R = \(\frac{44}{11}\) = 4

  ×4      ×4 

  16       28   (present age)

⇒ Hence, B's present age = 28 + 4 = 32

⇒ Age of B two years ago = 32 - 2 = 30 years