Thực hiện phép tính: a) 4/5 + 4/3 . -9/20                       b) 1/9 +2/3^2 -5/3 : căn 25

a)\(\frac{4}{5} + \frac{4}{3}.\left( {\frac{{ - 9}}{{20}}} \right)\)\( = \frac{4}{5} + \frac{{ - 3}}{5}\)\( = \frac{1}{5}\)

b)\[{\left( {\frac{1}{9} + \frac{2}{3}} \right)^2} - \frac{5}{3}:\sqrt {25} \]

\( = {\left( {\frac{7}{9}} \right)^2} - \frac{5}{3}.\frac{1}{5}\)

\( = \frac{{49}}{{81}} - \frac{1}{3}\)

\( = \frac{{49}}{{81}} - \frac{{27}}{{81}}\)

\( = \frac{{22}}{{81}}.\)