Ta có: \(\left(\frac{2}{99}+\frac{5}{7}\right):\frac{4}{7}+\frac{7}{4}\cdot\frac{97}{99}\)
\(=\left(\frac{2}{99}+\frac{5}{7}\right)\cdot\frac{7}{4}+\frac{7}{4}\cdot\frac{97}{99}\)
\(=\frac{7}{4}\cdot\left(\frac{2}{99}+\frac{5}{7}+\frac{97}{99}\right)\)
\(=7\cdot\left(1+\frac{5}{7}\right)\)
\(=7\cdot1+7\cdot\frac{5}{7}\)
\(=7+5=12\)