《2025年口算训练六年级数学上册人教版双色升级版》

答案： $\frac {2}{45} \frac {1}{5} \frac {8}{15}$
$\frac {5}{32} \frac {3}{28} \frac {5}{28}$
$\frac {2}{7} \frac {1}{120} \frac {1}{40}$
$\frac {5}{48} \frac {1}{12} \frac {7}{27} \frac {2}{5}$

答案： $\frac{4}{5} + \frac{4}{5} + \frac{4}{5} = \frac{4}{5} × 3 = \frac{12}{5}$
$\frac{3}{7} + \frac{3}{7} + \frac{3}{7} + \frac{3}{7} = \frac{3}{7} × 4 = \frac{12}{7}$
$\frac{5}{9} + \frac{5}{9} + \frac{5}{9} = \frac{5}{9} × 3 = \frac{15}{9} = \frac{5}{3}$
$\frac{5}{12} + \frac{5}{12} + \frac{5}{12} + \frac{5}{12} = \frac{5}{12} × 4 = \frac{20}{12} = \frac{5}{3}$
$\frac{11}{20} + \frac{11}{20} + \frac{11}{20} = \frac{11}{20} × 3 = \frac{33}{20}$
$\frac{4}{25} + \frac{4}{25} + \frac{4}{25} = \frac{4}{25} × 3 = \frac{12}{25}$
$\frac{7}{11} + \frac{7}{11} + \frac{7}{11} = \frac{7}{11} × 3 = \frac{21}{11}$
$\frac{3}{38} = \frac{1}{38} × 3 = \frac{1}{38} + \frac{1}{38} + \frac{1}{38}$
$\frac{15}{17} = \frac{5}{17} × 3 = \frac{5}{17} + \frac{5}{17} + \frac{5}{17}$
$\frac{3}{20} = \frac{1}{20} × 3 = \frac{1}{20} + \frac{1}{20} + \frac{1}{20}$
$\frac{9}{8} = \frac{3}{8} × 3 = \frac{3}{8} + \frac{3}{8} + \frac{3}{8}$
$\frac{15}{7} = \frac{5}{7} × 3 = \frac{5}{7} + \frac{5}{7} + \frac{5}{7}$
$\frac{18}{23} = \frac{6}{23} × 3 = \frac{6}{23} + \frac{6}{23} + \frac{6}{23}$