第30页 - 亮点给力提优课时作业本五年级数学江苏版

$ =\frac {7}{15}+\frac {8}{15}-\frac {5}{12}-\frac {7}{12}$

$=1-(\frac {5}{12}+\frac {7}{12})$

$=1-1$

$=0$

$ =\frac {11}{10}+\frac {13}{10}+(\frac {17}{6}-\frac {5}{6})$

$=\frac {12}{5}+2$

$=4\frac {2}{5}$

$ =5+(\frac {5}{8}-\frac {3}{8})$

$=5+\frac {1}{4}$

$=5\frac {1}{4}$

$ =\frac {17}{10}-\frac {7}{10}-\frac {5}{6}$

$=1-\frac {5}{6}$

$=\frac {1}{6}$