Discussion

Solve:

$\frac{{(6.9)}^3+{(2.7)}^3+{(5.8)}^3-3\times 6.9\times 2.7\times 5.8}{{(6.9)}^2+{(2.7)}^2+{(5.2)}^2-(6.9)(2.7)-(2.7)(5.8)-(5.8)(5.9)}$