The sum of A and B's age is 43 years.
Let B = B's PRESENT age
So, 43 - B = A's PRESENT age

In 11 years....
B + 11 = B's age IN 11 YEARS
(43 - B) + 11 = A's age IN 11 YEARS

..., A's age will be 7/6 times B's age.
We can write: (43 - B) + 11 = (7/6)(B + 11)
Simplify the left side: 54 - B = (7/6)(B + 11)
To eliminate the fraction, multiply both sides of the equation by 6 to get: 6(54 - B) = (7)(B + 11)
Expand: 324 - 6B = 7B + 77
Add 6B to both sides of the equation: 324 = 13B + 77
Subtract 77 from both sides: 247 = 13B
Solve: B = 247/13 = 19

Answer: D