Ratio of A's age to B's age is 4 : 3. 'A' will be 26 years old after 6 years. The age of B now is = ?

Ratio of A's age to B's age is 4 : 3 = 4x : 3x
After 6 years A's age = 4x + 6
∴ According to question,
$$\eqalign{ & 4x + 6 = 26 \cr & \boxed{x = 5} \cr & \therefore {\text{B's age}} = 3x \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 3 \times 5 \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 15 \cr} $$