Let the present ages of A, B, F and S be ‘a’, ‘b’, ‘c’ and ‘d’ respectively.
Given,
A is elder to B by 2 years
⇒ a = b + 2 -------- (1)
A’s father F is twice as old as A and B is twice as old as his sister S
⇒ c = 2a and b = 2d ------- (2)
Also, the ages of the father and sister differ by 40 years.
⇒ c – d = 40 ------- (3)
From [2], we have
⇒ 2a – b/2 = 40
Hence,
Age of 'A' is 26 years.