Đáp án:
Giải thích các bước giải:
$\dfrac{5}{7}+ \dfrac{7}{13}+ \dfrac{19}{13}+ \dfrac{6}{5}+ \dfrac{9}{7}+ \dfrac{9}{5}$
$= (\dfrac{5}{7}+ \dfrac{9}{7})+ (\dfrac{7}{13}+ \dfrac{19}{13})+ (\dfrac{6}{5}+ \dfrac{9}{5})$
$= \dfrac{14}{7}+ \dfrac{26}{13}+ \dfrac{15}{5}$
$= 2+ 2+ 3$
$= 7$