a)\(\dfrac{x-3}{27}\)=\(\dfrac{7}{21}\)
\(\dfrac{x-3}{27}=\dfrac{1}{3}\)
\(\dfrac{x-3}{27}=\dfrac{9}{27}\)
=>x-3=9
x=9+3
x=12
Vậy x=12
b)\(2\dfrac{x}{7}=\dfrac{153}{63}\)
\(2\dfrac{x}{7}=2\dfrac{27}{63}\)
=>\(\dfrac{x}{7}=\dfrac{27}{63}\)
\(\dfrac{x}{7}=\dfrac{3}{7}\)
=>x=3
Vậy x=3
c)\(\left(\dfrac{7}{3}x-\dfrac{6}{10}\right):3\dfrac{2}{5}=1\)
\(\left(\dfrac{7}{3}x-\dfrac{3}{5}\right):\dfrac{17}{5}=1\)
\(\dfrac{7}{3}x-\dfrac{3}{5}=\dfrac{17}{5}\)
\(\dfrac{7}{3}x=\dfrac{17}{5}+\dfrac{3}{5}\)
\(\dfrac{7}{3}x=\dfrac{20}{3}\)
\(x=\dfrac{20}{3}:\dfrac{7}{3}\)
\(x=\dfrac{20}{3}\cdot\dfrac{3}{7}\)
\(x=\dfrac{20}{7}\)
Vậy \(x=\dfrac{20}{7}\)
