Đáp án:
Giải thích các bước giải:
$\text{1) $\frac{3}{22}$ x $\frac{3}{11}$ x 22}$
$\text{= $\frac{9}{249}$ x 22}$
$\text{= $\frac{9}{11}$}$
$\text{2) ($\frac{1}{2}$ + $\frac{1}{3}$) x $\frac{2}{5}$}$
$\text{= $\frac{5}{6}$ x $\frac{2}{5}$}$
$\text{= $\frac{1}{3}$}$
$\text{3)$\frac{3}{5}$ x $\frac{17}{21}$ x $\frac{17}{21}$ x $\frac{2}{5}$}$
$\text{=$\frac{17}{21}$ x ($\frac{2}{5}$+ $\frac{3}{5}$)}$
$\text{=$\frac{17}{21}$ x 1}$
$\text{=$\frac{17}{21}$}$