Tính bằng cách hợp lý: 38*13-38*11

\[\frac{{38}}{{11}} + \left( {\frac{{16}}{{13}} + \frac{6}{{11}}} \right)\]

\[ = \frac{{38}}{{11}} + \frac{{16}}{{13}} + \frac{6}{{11}}\]

\[ = \left( {\frac{{38}}{{11}} + \frac{6}{{11}}} \right) + \frac{{16}}{{13}}\]

\[ = \frac{{44}}{{11}} + \frac{{16}}{{13}}\]

\[ = 4 + \frac{{16}}{{13}}\]

\[ = \frac{{52}}{{13}} + \frac{{16}}{{13}} = \frac{{68}}{{13}}\].