PROBLEMS ON AGES

4 years ago, the ratio of $\frac{1}{2}$ of A’s age at that time and four times of B’s age at the time was 5 : 12. Eight years hence, $\frac{1}{2}$ of A’s age at that time will be less than B’s age at that time by 2 years. What is B’s present age? [IBPS—RRB Officers Exam, 2015]