Đáp án:
a.2
b.10
Giải thích các bước giải:
a.$\dfrac{11}{9}+\dfrac{7}{9}=\dfrac{11+7}{9}=\dfrac{18}{9}=2$
b.$\dfrac{5}{7}.22\dfrac{6}{11}-\dfrac{5}{7}.8\dfrac{6}{11}$
$=\dfrac{5}{7}(22\dfrac{6}{11}-8\dfrac{6}{11})$
$=\dfrac{5}{7}((22+\dfrac{6}{11})-(8+\dfrac{6}{11}))$
$=\dfrac{5}{7}(22+\dfrac{6}{11}-8-\dfrac{6}{11})$
$=\dfrac{5}{7}(22-8+(\dfrac{6}{11}-\dfrac{6}{11}))$
$=\dfrac{5}{7}(14+0)$
$=\dfrac{5}{7}.14$
$=\dfrac{5.14}{7}$
$=\dfrac{5.2.7}{7}$
$=5.2$
$=10$
