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二、计算下面各题，怎样简便就怎样计算。
$\frac{1}{13} + \frac{12}{13}×(\frac{2}{5} - \frac{1}{3})$ $300÷(1 + 20\%)×40$ $(0.675×80 - 5.5)÷0.25$
$2.85×7.8 - 7.8×0.85$ $12×(\frac{5}{12} + \frac{7}{25})×25$ $69.8 - (9.8 + 45.25) - 5.75$
$1670 + 800×7÷40$ $3 - \frac{3}{8}÷\frac{7}{16} - \frac{1}{7}$ $\frac{1}{4} + \frac{1}{8} + \frac{1}{16} + \frac{1}{32} + \frac{1}{64} + \frac{1}{128}$
$\frac{2}{9}×40\% + \frac{7}{9}×40\%$ $(\frac{7}{6} - \frac{7}{12})÷\frac{7}{24} - \frac{2}{15}$ $\frac{1}{3}×[90\%÷(\frac{7}{16} - \frac{1}{4})]$
$19÷\frac{5}{9}×\frac{1}{6}÷\frac{1}{8}$ $\frac{1}{2}÷[(\frac{7}{9} - \frac{2}{3})×6]$ $1 - 20\%×2 - 25\%×2$
$\frac{1}{13} + \frac{12}{13}×(\frac{2}{5} - \frac{1}{3})$ $300÷(1 + 20\%)×40$ $(0.675×80 - 5.5)÷0.25$
$2.85×7.8 - 7.8×0.85$ $12×(\frac{5}{12} + \frac{7}{25})×25$ $69.8 - (9.8 + 45.25) - 5.75$
$1670 + 800×7÷40$ $3 - \frac{3}{8}÷\frac{7}{16} - \frac{1}{7}$ $\frac{1}{4} + \frac{1}{8} + \frac{1}{16} + \frac{1}{32} + \frac{1}{64} + \frac{1}{128}$
$\frac{2}{9}×40\% + \frac{7}{9}×40\%$ $(\frac{7}{6} - \frac{7}{12})÷\frac{7}{24} - \frac{2}{15}$ $\frac{1}{3}×[90\%÷(\frac{7}{16} - \frac{1}{4})]$
$19÷\frac{5}{9}×\frac{1}{6}÷\frac{1}{8}$ $\frac{1}{2}÷[(\frac{7}{9} - \frac{2}{3})×6]$ $1 - 20\%×2 - 25\%×2$
答案
$\frac{9}{65}$ 10000 194
15.6 209 9
1810 2 $\frac{63}{128}$
0.4 $\frac{28}{15}$ $\frac{8}{5}$
$\frac{228}{5}$ $\frac{3}{4}$ $\frac{1}{10}$
15.6 209 9
1810 2 $\frac{63}{128}$
0.4 $\frac{28}{15}$ $\frac{8}{5}$
$\frac{228}{5}$ $\frac{3}{4}$ $\frac{1}{10}$
