If the average arthimatic mean of 8,12,15,21. x an 11 is 17 than what is x ?

If the average arthimatic mean of 8,12,15,21. x an 11 is 17 than what is x ?

Explanation

As given:    (8 + 12 + 15 + 21 + x + 11)/ 6 = 17

(67+x)/6 = 17

67+x = 102

        x = 102-67

         x = 35