A) \(\frac{1}{2}\cdot\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{27}\right)\) 

\(=\frac{1}{2}\cdot\frac{1}{2}\)

\(=\frac{1}{4}\)

B)   \(\left(\frac{-5}{28}+1.75+\frac{8}{35}\right):\left(-3\frac{9}{20}\right)\)

\(=\left(\frac{-5}{28}+\frac{7}{4}+\frac{8}{35}\right):\frac{-69}{20}\)

\(=\frac{14}{5}:\frac{-69}{20}\)

\(=\frac{-56}{69}\)

\(x:\frac{5}{9}=2-\frac{1}{2}\)

\(x:\frac{5}{9}=\frac{3}{2}\)

\(x=\frac{3}{2}\times\frac{5}{9}\)

\(x=\frac{5}{6}\)

Tìm x

\(\left(2\frac{4}{5}.x+50\right):\frac{2}{3}=-51\)

các bạn bt làm giúp mình với 

\(x:\frac{5}{9}=2-\frac{1}{2}\)

\(x:\frac{5}{9}=\frac{3}{2}\)

\(x=\frac{3}{2}\times\frac{5}{9}\)

\(x=\frac{5}{6}\)

X:5/9 = 2 - 1/2

X : 5/9 = 3/2

X = 3/2 x 5/9

X = 5/6

À nhầm tại vì hôm qua mình không thấy câu hỏi của mình đâu cả , nên mới cho câu hỏi mới , mình xin lỗi các banjnhieeuf ạ !

a)\(\left(0,25^{10}\right).4^{10}.\sqrt{5^2-3^2}=\left(0,25.4\right)^{10}.\sqrt{25-9}=1^{10}.\sqrt{16}=1.4=4\)

b)\(\frac{\left(-3\right)^6.15^5+9^3.\left(-15\right)^6}{\left(-3\right)^{10}.5^5.2^3}=\frac{3^6.15^5+3^6.15^6}{3^{10}.5^5.2^3}=\frac{3^6.15^5.\left(1+15\right)}{3^{10}.5^5.2^3}\)\(=\frac{3^{11}.5^5.16}{3^{10}.5^5.2^3}=3.2=6\)

2)a)\(4-\left|x+\frac{2}{3}\right|=-1\Rightarrow\left|x+\frac{2}{3}\right|=5\Rightarrow\orbr{\begin{cases}x+\frac{2}{3}=5\\x+\frac{2}{3}=-5\end{cases}\Rightarrow}\orbr{\begin{cases}x=\frac{13}{3}\\x=\frac{-17}{3}\end{cases}}\)

b)\(\frac{x-2}{-9}=\frac{16}{2-x}\Rightarrow\left(x-2\right)^2=144\Rightarrow\orbr{\begin{cases}x-2=12\\x-2=-12\end{cases}\Rightarrow\orbr{\begin{cases}x=14\\x=-10\end{cases}}}\)

c)\(\frac{2}{3}x+\frac{1}{7}=\frac{5}{3}\Rightarrow\frac{2}{3}x=\frac{32}{21}\Rightarrow x=\frac{16}{7}\)