The father’s age is six times his son’s age. Four years hence, the age of the father will be four times his son’s age. The present ages (in years) of the son and the father are, respectively

Let the son be S, so the father is 6S. In four years 6S + 4 = 4(S + 4), giving 2S = 12 and S = 6, so the father is 36. The pair 4 and 24 fails the check, since in four years they would be 8 and 28, not a four-to-one ratio.