Rút gọn các phân số (theo mẫu):

Mẫu: \(\frac{{49}}{{21}} = \frac{{49:7}}{{21:7}} = \frac{7}{3}\)

a)\(\frac{{12}}{{20}} = ....................\)	b) \(\frac{{21}}{{28}} = ....................\)
c) \(\frac{{24}}{{66}} = ....................\)	d) \(\frac{{145}}{{15}} = ....................\)

Mẫu: 5 = \(\frac{5}{1}\)’

9 = …………...;

3 = …………...;

11 = …………...;

\(\frac{{3 \times 8 \times 13}}{{13 \times 3 \times 22}} = ...................\)

\(\frac{{11 \times 4 \times 7}}{{7 \times 11 \times 9}} = ...................\)

\(\frac{2}{3} = \frac{8}{{.....}}\)

\(\frac{{10}}{{30}} = \frac{{.....}}{{90}}\)

\(\frac{{25}}{{50}} = \frac{{.....}}{2}\)

\(\frac{{.....}}{7} = \frac{{21}}{{49}}\)

\(\frac{2}{9} = \frac{{16}}{{.....}}\)

\(\frac{5}{{.....}} = \frac{{30}}{{18}}\)

a) Mẫu: 1 : 4 = \(\frac{1}{4}\)

5 : 17 = …………..

4 : 25 = …………..

b) Mẫu: 12 : 3 = \(\frac{{12}}{3}\)

24 : 8 = …………..

36 : 6 = …………..

\(\frac{1}{3}\);

\(\frac{2}{8}\);

\(\frac{6}{{24}}\);

\(\frac{{11}}{{12}}\);

\(\frac{{33}}{{44}}\)