Tìm x biết 1,16 trừ x nhân 5,25 trên 10 5 phần 9 trừ 7 1 phần 4

* Hướng dẫn giải

Đáp án C

$$\begin{gathered} \frac{\left(1,16-x\right).5,25}{\left(10{\displaystyle \frac{5}{9}}-7{\displaystyle \frac{1}{4}}\right).2{\displaystyle \frac{2}{17}}}=75\% \\ \iff \frac{\left({\displaystyle \frac{29}{25}}-x\right).{\displaystyle \frac{21}{4}}}{\left({\displaystyle \frac{95}{9}}-{\displaystyle \frac{29}{4}}\right).{\displaystyle \frac{36}{17}}}=\frac{3}{4} \\ \iff \frac{\left({\displaystyle \frac{29}{25}-x}\right).{\displaystyle \frac{21}{4}}}{{\displaystyle \frac{119}{36}}.{\displaystyle \frac{36}{17}}}=\frac{3}{4} \\ \iff \frac{\left({\displaystyle \frac{29}{25}-x}\right).{\displaystyle \frac{21}{4}}}{{\displaystyle 7}}=\frac{3}{4} \\ \iff \left(\frac{29}{25}-x\right).\frac{21}{4}=\frac{21}{4} \\ \iff \frac{29}{25}-x=1 \\ \iff x = \frac{4}{25} \end{gathered}$$