2 - [x : 4/7 - \(2\frac{3}{4}\)] * 9,8 = 0
=> 2 - [x : 4/7 - 11/4] = 0
=> x : 4/7 -11/4 = 2
=> x : 4/7 = 2 + 11/4
=> x : 4/7 = 19/4
=> x = 19/4 * 4/7
=> x = 19/7
Vậy x = 19/7
\(3\frac{1}{4}\cdot\left(8\frac{1}{2}-x\div\frac{1}{3}\right)=3,21\)
\(\Rightarrow\frac{13}{4}\cdot\left(\frac{17}{2}-x\div\frac{1}{3}\right)=3,21\)
\(\Rightarrow3,25\cdot\left(8,5-x\div\frac{1}{3}\right)=3,21\)
\(\Rightarrow8,5-x\div\frac{1}{3}=3,21\div3,25\)
\(\Rightarrow8,5-x\div\frac{1}{3}=\frac{321}{325}\)
\(\Rightarrow x\div\frac{1}{3}=8,5\div\frac{321}{325}\)
\(\Rightarrow x\div\frac{1}{3}=\frac{5525}{642}\)
\(\Rightarrow x=\frac{5525}{642}\cdot\frac{1}{3}=2,868639668\)
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