第8页 - 江苏版启东中学作业本七年级数学（上下册）

$=-(8+1)+(10+2)$

$=-9+12$

$=3$

=(-27+32+8)+72

=-67+72

=5

$=-(27-17)-(14-8)$

$=-10-6$

$=-16$

$=(-1 \frac {1}{2})+4 \frac {1}{4}+2 \frac {3}{4}+(-5 \frac {1}{2})$

$=-(1 \frac {1}{2}+5 \frac {1}{2})+(4 \frac {1}{4}+2 \frac {3}{4})$

$=-7+7$

$=0$

$=-(\frac {3}{7}-\frac {2}{7})-(1 \frac {3}{5}-\frac {3}{5})$

$=-\frac {1}{7}-1$

$=-1\frac {1}{7}$

$=(\frac 12-\frac 12)+-(\frac 23+\frac 12)+\frac {4}{7}$

$=0-1+\frac {4}{7}$

$=-\frac {3}{7}$

$=(12-2)+(7 \frac {1}{3}-\frac {4}{3})$

$=10+6$

$=16$

$=(4 \frac {1}{3}-1 \frac {1}{3})-(5.5+3 \frac {1}{2})$

$=3-9$

$=-6$

$=(0.56+0.44)-(0.9+8.1)$

$=1-9$

$=-8$

$=(1-2)+(3-4)+···+(99-100)$

$=-1-1-···-1$

$=-50$