Phép tính đúng là:

1/11

Phép tính đúng là:

\[\frac{4}{5}{\rm{ + }}\frac{5}{8}{\rm{ }} = {\rm{ }}\frac{{57}}{{45}}\]

\[\frac{{17}}{{15}} - \frac{3}{5} = \frac{8}{{15}}\]

\[\frac{3}{5}{\rm{ + }}\frac{9}{{20}}{\rm{ }} = {\rm{ }}\frac{{12}}{{20}}\]

\[\frac{{34}}{7}{\rm{ - }}\frac{1}{{14}}{\rm{ }} = {\rm{ }}\frac{{33}}{7}\]

Giải thích

Đáp án đúng là: B

\(\frac{4}{5}\,\, + \,\,\frac{5}{8}\,\, = \,\,\frac{{32}}{{40}}\,\, + \,\,\frac{{25}}{{40}}\,\, = \,\,\frac{{55}}{{40}}\)

\[\frac{{17}}{{15}} - \frac{3}{5} = \frac{{17}}{{15}} - \frac{9}{{15}} = \frac{8}{{15}}\]

\(\frac{3}{5}\,\, + \,\,\frac{9}{{20}}\,\, = \,\,\frac{{12}}{{20}}\,\, + \,\,\frac{9}{{20}}\,\, = \,\,\frac{{21}}{{20}}\)

\(\frac{{34}}{7}\,\, - \,\,\frac{1}{{14}}\,\, = \,\,\frac{{68}}{{14}}\,\, - \,\,\frac{1}{{14}}\,\, = \,\,\frac{{67}}{{14}}\)