câu 1 = 0
câu 2 : X=\(\frac{16}{105}\)
X =\(\frac{180}{77}\)
X = 63
(18\(\dfrac{1}{2}+5\dfrac{3}{8}-7\dfrac{5}{24}\)) - 16\(\dfrac{2}{3}\)
=( \(\dfrac{37}{2}\) + \(\dfrac{43}{8}\) - \(\dfrac{171}{24}\) ) - \(\dfrac{50}{3}\)
= \(\dfrac{50}{3}\) - \(\dfrac{50}{3}\)
=0
a)\(x:\dfrac{2}{5}=\dfrac{4}{7}:\dfrac{3}{2}\)
\(x:\dfrac{2}{5}=\dfrac{8}{21}\)
x =\(\dfrac{8}{21}\times\dfrac{2}{5}\)
x= \(\dfrac{16}{105}\)
b)\(\dfrac{12}{17}:x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\dfrac{12}{17}:x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\dfrac{12}{17}:x=\dfrac{11}{15}\)
\(x=\dfrac{12}{17}:\dfrac{11}{15}\)
\(x=\dfrac{180}{187}\)
\(\dfrac{42}{25}:\dfrac{x}{9}=\dfrac{6}{5}\)
\(\dfrac{x}{9}=\dfrac{42}{25}:\dfrac{6}{5}\)
\(\dfrac{x}{9}=\dfrac{7}{5}\)
\(\dfrac{x}{9}=\dfrac{63}{45}\)
x = 63