Знаменатель 6:

[tex] \frac{10}{12} = \frac{10 \div 2}{1 2\div 2} = \frac{5}{6} \\ \frac{1}{2} = \frac{1 \times 3}{2 \times 3} = \frac{3}{6} \\ \frac{4}{8} = \frac{4 \div 4 \times 3}{8 \div 4 \times 3} = \frac{1 \times 3}{2 \times 3} = \frac{3}{6} \\ 7 = \frac{7 \times 6}{1 \times 6} = \frac{42}{6} \\ \frac{17}{34} = \frac{17 \div 17 \times 3}{34 \div 17 \times 3} = \frac{1 \times 3}{2 \times 3} = \frac{3}{6} [/tex]

Знаменатель 18:

[tex] \frac{21}{54} = \frac{21 \div 3}{54 \div 3} = \frac{7}{18} \\ \frac{2}{9} = \frac{2 \times 2}{9 \times 2} = \frac{4}{18} \\ 2 = \frac{2 \times 18}{1 \times 18} = \frac{36}{18} \\ \frac{15}{27} = \frac{15 \div 3 \times 2}{27 \div 3 \times 2} = \frac{5 \times 2}{9 \times 2} = \frac{10}{18} \\ \frac{65}{78} = \frac{65 \div 13 \times 3}{78 \div 13 \times 3} = \frac{5 \times 3}{6 \times 3} = \frac{15}{18} [/tex]

Знаменатель 28:

[tex] \frac{6}{56} = \frac{6 \div 2}{56 \div 2} = \frac{3}{28} \\ \frac{3}{4} = \frac{3 \times 7}{4 \times 7} = \frac{21}{28} \\ \frac{2}{7} = \frac{2 \times 4}{7 \times 4} = \frac{8}{28} \\ \frac{15}{35} = \frac{15 \div 5 \times 4}{35 \div 5 \times 4} = \frac{3 \times 4}{ 7\times 4} = \frac{12}{28} \\ \frac{6}{21} = \frac{6 \div 3 \times 4}{2 1\div 3 \times 4} = \frac{2 \times 4}{7 \times 4} = \frac{8}{28} [/tex]