問題
$1.4\div\left(2-\square\right)-0.8\times\dfrac{3}{4}=0.6$
解説
$0.8=\dfrac{4}{5}$より, $0.8\times\dfrac{3}{4}=\dfrac{4}{5}\times\dfrac{3}{4}=\dfrac{3}{5}=0.6$
$1.4\div\left(2-\square\right)-0.6=0.6$
$1.4\div\left(2-\square\right)=1.2$
$1.4=\dfrac{7}{5},\ 1.2=\dfrac{6}{5}$より, $\dfrac{7}{5}\div\left(2-\square\right)=\dfrac{6}{5}$なので,
$2-\square=\dfrac{7}{5}\div\dfrac{6}{5}=\dfrac{7}{5}\times\dfrac{5}{6}=\dfrac{7}{6}$
以上より, $\square=2-\dfrac{7}{6}=\dfrac{12-7}{6}=$$\dfrac{5}{6}$となります.
