第23页 - 苏科版七年级伴你学数学答案（上下册）

-180

$[(-4\frac{7}{9})+(-2\frac{2}{9})]+[(+3\frac{1}{6})+(-6\frac{1}{6})]$

B

解:原式=(18-24)+(15-15)

=-6

解:原式=(19.96-0.96)+5.2-(3.8+0.2)

=19+5.2-4

=20.2

解:50×10+(2.5-7.5-3+5.5-12-6+4.5+8+2-2)=492(kg)

0

解:$原式=-(8\frac {3}{7}+21\frac {4}{7})+(3\frac {1}{2}-7\frac {1}{2})$

$=-30-4$

$=-34$

解:原式=(2-1)+(4-3)+···+(100-99)

=1×50

=50

解:(1)原式=-5+5=0

(2)原式=-3+[-4,-7]

=-3-4

=-7