Age of A is 6 years more than three times the age of B. After three years, A's age will be 8 years more than twice the age of B. The average of present ages of A and (in years) is:

Let the present age of B = x

                                           A                        B

Present Age                  3x+6                     x

After 3 years        3x+6+3 = 3x+9           x+3

Given, After 3 years A's age will be 8 years more than twice the age of B

$$=$$>           3x+9 = 2(x+3)+8                

                 3x+9 = 2x+6+8

                        x = 5

Average of Present ages of A and B = $$\ \frac{\ 3x+6+x}{2}$$

                                                                = $$\ \frac{\ 4x+6}{2}$$

                                                                = $$\ \frac{\ 4\left(5\right)+6}{2}$$

                                                                =  13