Six years ago, the ratio of ages of A to B was 7 : 5. After 4 years from now, the ratio of their ages will be 11 : 9. What is A’s age at present?

A

$$24\frac{1}{2}$$ years

B

$$22\frac{1}{2}$$ years

C

$$23\frac{1}{2}$$ years

D

$$21\frac{1}{2}$$ years