Đúng ghi Đ, sai ghi S vào ô trống:

Giải thích

\[\frac{1}{5} + \frac{3}{7} = \frac{7}{{35}} + \frac{{15}}{{35}} = \frac{{22}}{{35}}\]

\[\frac{{12}}{7} - \frac{5}{4} = \frac{{48}}{{28}} - \frac{{35}}{{28}} = \frac{{13}}{{28}}\]

\[\frac{7}{2} + \frac{1}{3} + 1 = \frac{{21}}{6} + \frac{2}{6} + \frac{6}{6} = \frac{{29}}{6}\]

\[\frac{2}{{11}} + \frac{4}{3} = \frac{6}{{33}} + \frac{{44}}{{33}} = \frac{{50}}{{33}}\]

\[\frac{7}{3} - \frac{2}{5} = \frac{{35}}{{15}} - \frac{6}{{15}} = \frac{{29}}{{15}}\]

\[\frac{9}{2} - \frac{1}{5} - 1 = \frac{{45}}{{10}} - \frac{2}{{10}} - \frac{{10}}{{10}} = \frac{{33}}{{10}}\]