Question

[Văn Thị Quỳnh Trâm]

tính bằng cách thuận tiện

 \(\frac{4}{5}+\left(\frac{1}{5}-\frac{1}{7}\right):\frac{2}{7}\)

Answer 1

[Trần Kiều Thi]

\(\frac{4}{5}+\frac{2}{35}\times\frac{7}{2}=\frac{4}{5}+\frac{1}{5}=1\)

Answer 2

[KAl(SO4)2·12H2O]

\(\frac{4}{5}+\left(\frac{1}{5}-\frac{1}{7}\right):\frac{2}{7}\)

\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\frac{1}{7}:\frac{2}{7}\)

\(=\frac{5}{5}-\frac{1}{2}\)

\(=1-\frac{1}{2}=\frac{1}{2}\)