Giải thích các bước giải:
a/ $11\dfrac{1}{4}-(2\dfrac{5}{7}+5\dfrac{1}{4})$
$=\dfrac{45}{4}-(\dfrac{19}{7}+\dfrac{21}{4})$
$=\dfrac{45}{4}-\dfrac{223}{28}$
$=\dfrac{23}{7}$
b/ $(-\dfrac{5}{9}).\dfrac{3}{11}+(-\dfrac{13}{18}).\dfrac{3}{11}$
$=\dfrac{3}{11}.(-\dfrac{5}{9}-\dfrac{13}{18})$
$=\dfrac{3}{11}.(-\dfrac{10}{18}-\dfrac{13}{18})$
$=\dfrac{3}{11}.(-\dfrac{23}{18})$
$=-\dfrac{23}{66}$
Chúc bạn học tốt !!!
