4) A father is 46 years old and the sum of the ages of his three children is 22. In how many years will the father's age be equal to the sum of the ages of the children?
(A) 6
(B) 8
(C) 10
(D) 12
(E) never.
4) The answer is (D)

Every year that passes, the father's age increases by one while the sum of the children's ages increases by three, so the difference decreases by two and thus cancels out after twelve years.