\(\begin{array}{l}a)\frac{{ - 6}}{{18}} + \frac{{18}}{{27}}\\ = \frac{{ - 1}}{3} + \frac{2}{3}\\ = \frac{1}{3}\\b)2,5 - ( - \frac{6}{9})\\ = \frac{{25}}{{10}} + \frac{6}{9}\\ = \frac{5}{2} + \frac{2}{3}\\ = \frac{{15}}{6} + \frac{4}{6}\\ = \frac{{19}}{6}\\c) - 0,32.( - 0,875)\\ = \frac{{ - 32}}{{100}}.( - \frac{{875}}{{1000}})\\ = \frac{{ - 8}}{{25}}.(\frac{{ - 7}}{8})\\ = \frac{8}{{25}}.\frac{7}{8}\\ = \frac{7}{{25}}\\d)( - 5):2\frac{1}{5}\\ = ( - 5):\frac{{11}}{5}\\ = ( - 5).\frac{5}{{11}}\\ = \frac{{ - 25}}{{11}}\end{array}\)

1/ \(\frac{9.5^{20}.27^9-3.9^{15}.25^9}{7.3^{29}.125^6-3.3^9.15^{19}}\)

\(=\frac{5^{20}.3^{29}-3^{31}.5^{18}}{7.3^{29}.5^{18}-3^{29}.5^{19}}=\frac{3^{29}.5^{18}.\left(25-9\right)}{3^{29}.5^{18}.\left(7-5\right)}=\frac{16}{2}=8\)

CÁC BÀI CÒN LẠI TƯƠNG TỰ HẾT NHÉ E

a)\(\frac{-5}{13}+\left(\frac{3}{5}+\frac{3}{13}-\frac{4}{10}\right)=\frac{-5}{13}-\frac{3}{5}-\frac{3}{13}+\frac{4}{10}=\left(\frac{-5}{13}-\frac{3}{13}\right)+\frac{4}{10}-\frac{3}{5}=\frac{-5-3}{13}+\left(\frac{4}{10}-\frac{6}{10}\right)=\frac{-8}{13}+\frac{-2}{10}=\frac{-80}{130}+\frac{-26}{130}=\frac{-106}{130}=\frac{-53}{65}\)

=>\(5\cdot\dfrac{3\sqrt{x-3}}{5}-7\cdot\dfrac{2\sqrt{x-3}}{3}-7\cdot\sqrt{x^2-9}+18\cdot\sqrt{\dfrac{9}{81}\left(x^2-9\right)}=0\)

=>\(3\cdot\sqrt{x-3}-\dfrac{14}{3}\sqrt{x-3}=7\cdot\sqrt{x^2-9}-18\cdot\dfrac{3}{9}\cdot\sqrt{x^2-9}\)

=>\(-\dfrac{5}{3}\sqrt{x-3}=\sqrt{x^2-9}\)

=>\(\sqrt{x-3}\left(\sqrt{x+3}+\dfrac{5}{3}\right)=0\)

=>x-3=0

=>x=3

\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}+\frac{16}{24}+\frac{2}{3}\)

=\(\frac{1}{3}+\frac{1}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)

\(=\frac{8}{3}\)

\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}-\frac{-16}{24}+\frac{2}{3}\)

\(=\frac{9}{27}+\frac{8}{24}+\frac{18}{27}+\frac{16}{24}+\frac{2}{3}\)

\(=\frac{1}{3}+\frac{1}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)

\(=\left[\frac{1}{3}+\frac{2}{3}\right]+\left[\frac{1}{3}+\frac{2}{3}\right]+\frac{2}{3}\)

\(=1+1+\frac{2}{3}=2+\frac{2}{3}=\frac{8}{3}\)

\(\frac{9}{27}+\frac{8}{24}+\frac{18}{27}-\frac{-16}{24}+\frac{2}{3}\)

\(\frac{1}{3}+\frac{1}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)

\(\frac{2}{3}+\frac{2}{3}+\frac{2}{3}+\frac{2}{3}\)

\(\frac{8}{3}\)

thực hiện phép tính nha cám ơn m.ng

a) \(\frac{5}{9}:\frac{13}{7}+\frac{5}{9}:\frac{13}{9}-1\frac{2}{3}\\ =\frac{5}{9}\cdot\frac{7}{13}+\frac{5}{9}\cdot\frac{9}{13}-\frac{5}{3}\\ =\frac{5}{9}\left(\frac{7}{13}+\frac{9}{13}\right)-\frac{5}{3}\\ =\frac{5}{9}\cdot\frac{16}{13}-\frac{5}{3}\\ =\frac{80}{117}-\frac{5}{3}\\ =\frac{80}{117}-\frac{195}{117}=\frac{-115}{117}\)

b) \(\left(15-6\frac{13}{18}\right):11\frac{1}{27}-2\frac{1}{8}:1\frac{11}{40}\\ =\left(\frac{270}{18}-\frac{121}{18}\right):\frac{298}{27}-\frac{17}{8}:\frac{51}{40}\\ =\frac{149}{18}\cdot\frac{27}{298}-\frac{17}{8}\cdot\frac{40}{51}\\ =\frac{3}{4}-\frac{5}{3}\\ =\frac{9}{12}-\frac{20}{12}=\frac{-11}{12}\)