第18页 - 江苏版启东中学作业本七年级数学（上下册）

$=2.5×\frac {8}{5}×\frac {1}{4}$

$=1$

$=25×\frac {1}{5}×\frac {1}{5}×\frac {4}{3}$

$=\frac {4}{3}$

$=-12×\frac {4}{3}×\frac {1}{5}$

$=-\frac {16}{5}$

$=\frac {11}{5}×\frac {25}{11}×\frac {2}{5}$

$=2$

$=2.1×\frac {10}{7}×\frac {10}{7}$

$=\frac {30}{7}$

$=8×\frac {1}{4}×\frac {4}{15}$

$=\frac {8}{15}$

$=3×6×\frac {1}{2}×\frac {1}{2}$

$=\frac {9}{2}$

$=\frac {4}{7}×\frac {14}{3}×\frac {7}{3}$

$=-\frac {56}{9}$

$=-3×\frac {4}{7}×\frac {3}{4}×\frac {7}{3}×\frac {1}{9}$

$=-\frac {1}{3}$

$=-\frac {1}{42}÷(\frac {7}{42}-\frac {9}{42}+\frac {28}{42}-\frac {12}{42})$

$=-\frac {1}{42}÷\frac {14}{42}$

$=-\frac {1}{14}$