Viết số thích hợp vào chỗ chấm.
Giải thích
a) \[\frac{7}{{11}}\,\, = \,\,\frac{{{\bf{21}}}}{{33}}\,\, = \,\,\frac{{42}}{{{\bf{66}}}}\]
b) \[\frac{{54}}{{81}}\,\, = \,\,\frac{{\bf{6}}}{9}\,\, = \,\,\frac{{\bf{2}}}{3}\]
a) \[\frac{7}{{11}}\,\, = \,\,\frac{{{\bf{21}}}}{{33}}\,\, = \,\,\frac{{42}}{{{\bf{66}}}}\]
b) \[\frac{{54}}{{81}}\,\, = \,\,\frac{{\bf{6}}}{9}\,\, = \,\,\frac{{\bf{2}}}{3}\]