Mean

What is the mean of 80, 92, 77, 83, 72, 91, 84?

$\begin{array}{|rcll|} \hline && 80 + \frac{0+12-3+3-8+11+4}{7} \\ &=& 80 + \frac{12-8+11+4}{7} \\ &=& 80 + \frac{27-8}{7} \\ &=& 80 + \frac{19}{7} \\ &=& 80 + 2\frac{5}{7} \\ &=& 82\frac{5}{7} \\ &=& \frac{579}{7} \\ &=& 82.7142857143 \\ \hline \end{array}$