Wykonajmy obliczenia.

a)

$3\cdot \frac{7}{8}=\frac{3\cdot 7}{8}=\frac{21}{8}=2\frac{5}{8}$

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b)

$\frac{8}{7}\cdot 3=\frac{8\cdot 3}{7}=\frac{24}{7}=3\frac{3}{7}$

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c)

$2\cdot 1\frac{1}{7}=2\cdot \frac{8}{7}=$

$=\frac{2\cdot 8}{7}=\frac{16}{7}=2\frac{2}{7}$

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d)

$2\frac{1}{5}\cdot 3=\frac{11}{5}\cdot 3=$

$=\frac{11\cdot 3}{5}=\frac{33}{5}=6\frac{3}{5}$

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e)

$5\cdot 10\frac{1}{2}=5\cdot \frac{21}{2}=$

$=\frac{5\cdot 21}{2}=\frac{105}{2}=52\frac{1}{2}$

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f)

$10\cdot 8\frac{2}{3}=10\cdot \frac{26}{3}=$

$=\frac{10\cdot 26}{3}=\frac{260}{3}=86\frac{2}{3}$

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g)

$5\cdot \frac{7}{10}=\frac{5\cdot 7}{10}=\frac{35}{10}=3\frac{5}{10}=3\frac{1}{2}$

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h)

$\frac{2}{7}\cdot 14=\frac{2\cdot {\cancel{14}}^2}{{\cancel{7}}_1}=\frac{4}{1}=4$

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i)

$\frac{5}{18}\cdot 12=\frac{5\cdot {\cancel{12}}^2}{{\cancel{18}}_3}=\frac{10}{3}=3\frac{1}{3}$

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j)

$4\cdot 5\frac{5}{12}=4\cdot \frac{65}{12}=\frac{{\cancel{4}}^1\cdot 65}{{\cancel{12}}_3}=\frac{65}{3}=21\frac{2}{3}$

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k)

$6\frac{3}{8}\cdot 6=\frac{51}{8}\cdot 6=\frac{51\cdot {\cancel{6}}^3}{{\cancel{8}}_4}=$

$=\frac{153}{4}=38\frac{1}{4}$

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l)

$3\cdot 5\frac{5}{6}=3\cdot \frac{35}{6}=\frac{{\cancel{3}}^1\cdot 35}{{\cancel{6}}_2}=$

$=\frac{35}{2}=17\frac{1}{2}$