The average of thirteen numbers is 80. The average of the first five numbers is 74.5 and that of the next five numbers is 82.5. The 11th number is 6 more than the 12th number and the 12th number is 6 less than the 13th number. What is the average of the 11th and the 13th numbers?
तेरह संख्याओं का औसत 80 है | पहली पांच संख्याओं का औसत 74.5 और अगली पांच संख्याओं का औसत 82.5 है | 11वीं संख्या 12वीं संख्या से 6 अधिक है तथा 12वीं संख्या 13वीं संख्या से 6 कम है | 11वीं तथा 13वीं संख्याओं का औसत ज्ञात करें |

Options

A. 87
B. 86
C. 86.5
D. 87.5