第28页

信息发布者:

2
3
$\frac{9}{8}$
$\frac{1}{5}$
$\frac{6}{5}$
$\frac{2}{7}$
40
180

$=\frac{21}{2}×\frac {8}{21}$
$=4$

$=\frac {35}{108}×\frac{18}{35}$
$=\frac {1}{6}$

$=\frac {4}{11}×\frac {33}{34}×\frac {17}{18}$
$=\frac{6}{17}×\frac{17}{18}$
$=\frac{1}{3}$
B
B
13
15

$140×\frac{3}{7}=60(千瓦.时)\ $
$140-60=80(千瓦.时)\ $
$60×0.35+80×0.55=65(元) $
$答:那么优优家这个月电费是65元。$
$\frac{1}{2}$

$\begin{aligned}&2025\times(1 - \frac{1}{2})\times(1 - \frac{1}{3})\times(1 - \frac{1}{4})\times\cdots\times(1 - \frac{1}{2025})\\=&2025\times\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times\cdots\times\frac{2024}{2025}\\=&2025\times\frac{1}{2025}\\=&1\end{aligned}$
答:这批建筑材料还剩下1吨。