Вычислите: -16/25+4/27+21/25+(-13/27).

\[- \frac{16}{25} + \frac{4}{27} + \frac{21}{25} + \left( - \frac{13}{27} \right) =\]

\[= \left( \frac{21}{25} - \frac{16}{25} \right) - \left( \frac{13}{27} - \frac{4}{27} \right) =\]

\[= \frac{5}{25} - \frac{9}{27} =\]

\[= \frac{1}{5} - \frac{1}{3} = \frac{3}{15} - \frac{5}{15} = - \frac{2}{15}\]