Tính nhanh A = (315.3 + 372.3 + 372.7 + 315.7): (26.13 + 74.14)

Ta có: (315.3 + 372.3 + 372.7 + 315.7): (26.13 + 74.14)

\[ = \frac{{(315 + 372).3 + (372 + 315).7}}{{26.13 + 74.14}}\]

\[ = \frac{{(315 + 372)(3 + 7)}}{{2.13.13 + 74.2.7}}\]

\[ = \frac{{687.10}}{{2(169 + 518)}}\]

\[ = \frac{{6870}}{{2.687}} = \frac{{6870}}{{1374}} = 5\]

Vậy A = 5