Ответ:

1)2112×87÷117=1124×87×711=24×81=3

7 и 11 сокрашаем получаем 24×1/8 тут тоже сокращаем 24 и 8 на 8= 3

2)3 \frac{2}{3} \times 4 \frac{7}{8} \div \frac{13}{16} = \frac{11}{3} \times 4 \times \frac{7}{8} \times \frac{16}{13} = \frac{11}{3} \times 4 \times 7 \times \frac{2}{13} = \frac{11}{3} \times \frac{4}{1} \times \frac{7}{1} \times \frac{2}{13} = \frac{616}{39} = 15 \frac{31}{39}2)332×487÷1613=311×4×87×1316=311×4×7×132=311×14×17×132=39616=153931

тут тоже сократили

3)1 \frac{1}{3} \times 2 \frac{2}{3} \div \frac{4}{9} = \frac{4}{3} \times 2 \times \frac{2}{3} \times \frac{9}{4} = \frac{1}{3} \times 2 \times \frac{2}{3} \times 9 = 2 \times \frac{2}{3} \times 3 = 2 \times 2 = 43)131×232÷94=34×2×32×49=31×2×32×9=2×32×3=2×2=4

4)6 \frac{4}{15} \times \frac{1}{2} \div 3 \frac{2}{15} = \frac{94}{15} \times \frac{1}{2} \times \frac{1}{3} \times \frac{2}{15} = \frac{94}{15} \times \frac{1}{3} \times \frac{1}{15} = \frac{94}{675}4)6154×21÷3152=1594×21×31×152=1594×31×151=67594

5)8 \frac{1}{3} \times 1 \frac{5}{7} \div 2 \frac{8}{21} = \frac{25}{3} \times \frac{5}{7} \times \frac{1}{2} \times \frac{8}{21} = \frac{25}{5} \times \frac{5}{7} \times \frac{4}{21} = \frac{500}{441} = 1 \frac{59}{441}5)831×175÷2218=325×75×21×218=525