Đáp án:
$(\dfrac35+\dfrac{-2}7)+\dfrac{-1}5=\dfrac{4}{35}$
Giải thích các bước giải:
$(\dfrac35+\dfrac{-2}7)+\dfrac{-1}5$
$=\dfrac35+\dfrac{-2}7+\dfrac{-1}5$
$=\dfrac35+\dfrac{-1}5+\dfrac{-2}7$
$=\dfrac35-\dfrac{1}5-\dfrac{2}7$
$=\dfrac{3-1}{5}-\dfrac27$
$=\dfrac25-\dfrac27$
$=\dfrac{14}{35}-\dfrac{10}{35}$
$=\dfrac{14-10}{35}$
$=\dfrac{4}{35}$