Viết dấu “+” hoặc “-” vào ô trống

a) \(\frac{{17}}{{20}}\,\) + \(\frac{5}{6}\,\, = \,\,\frac{{101}}{{60}}\)

Giải thích:

\(\frac{{17}}{{20}}\,\, - \,\,\frac{5}{6}\,\, = \,\,\frac{{51}}{{60}}\,\, - \,\,\frac{{50}}{{60}}\,\, = \,\,\frac{1}{{60}}\)

\(\frac{{17}}{{20}}\,\, + \,\,\frac{5}{6}\,\, = \,\,\frac{{51}}{{60}}\,\, + \,\,\frac{{50}}{{60}}\,\, = \,\,\frac{{101}}{{60}}\)

b) \(\frac{{35}}{{21}}\,\) - \(\frac{4}{5}\,\, = \,\,\frac{{13}}{{15}}\)

Giải thích:

\(\frac{{35}}{{21}} - \frac{4}{5} = \frac{{175}}{{105}} - \frac{{84}}{{105}} = \frac{{91}}{{105}} = \frac{{13}}{{15}}\)

\(\frac{{35}}{{21}} + \frac{4}{5} = \frac{{175}}{{105}} + \frac{{84}}{{105}} = \frac{{259}}{{105}} = \frac{{37}}{{15}}\)

c) \(\frac{{23}}{{12}}\,\) + \(\frac{1}{5}\,\) - \(\frac{3}{{20}}\,\, = \,\,\frac{{59}}{{30}}\)

Giải thích:

\(\frac{{23}}{{12}} + \frac{1}{5} - \frac{3}{{20}} = \frac{{115}}{{60}} + \frac{{12}}{{60}} - \frac{9}{{60}} = \frac{{118}}{{60}} = \frac{{59}}{{30}}\)