\(A=\frac{7.9+14.27+21.36}{21.27+42.81+63.108}\)
\(A=\frac{7.9+7.2.27+7.3.36}{7.3.27+7.6.81+7.9.108}\)
\(A=\frac{7.9+7.54+7.108}{7.81+7.486+7.972}\)
\(A=\frac{7.\left(9+54+108\right)}{7.\left(81+486+972\right)}\)
\(A=\frac{7.171}{7.1539}=\frac{171}{1539}=\frac{1}{9}\)
7.9+7.54+7.108
21.27+21.162+21.36
7.(9+54+108)
21.(27+162+36)
7.171
21.225
7.32.19
3.7.32.52
19
3.52
19
75