Đáp án+giải thích các bước giải:
Bài 1:
$\dfrac{12}{5}$ - $2$ = $\dfrac{12}{5}$ - $\dfrac{10}{2}$ = $\dfrac{2}{5}$
$\dfrac{3}{5}$ x $\dfrac{2}{3}$ =$\dfrac{6}{15}$ = $\dfrac{2}{5}$
Bài 2:
$\dfrac{3}{5}$ x $\dfrac{2}{3}$ : $\dfrac{1}{2}$ = $\dfrac{4}{5}$
$\dfrac{2}{3}$ x ($\dfrac{1}{2}$ + $\dfrac{1}{3}$ ) = $\dfrac{5}{9}$
$\dfrac{5}{7}$ - $\dfrac{2}{5}$ : $\dfrac{11}{7}$ = $\dfrac{177}{385}$
Bài 3:
$15\dfrac{1}{3}$ = $\dfrac{46}{3}$
$205\dfrac{5}{30}$ = $\dfrac{1231}{6}$
$42\dfrac{14}{15}$ = $\dfrac{644}{15}$
Bài 4:
$\dfrac{37}{6}$ = $6\dfrac{1}{6}$
$\dfrac{12}{5}$ = $2\dfrac{2}{5}$
$\dfrac{108}{9}$ = $11\dfrac{9}{9}$