第39页

信息发布者：
$ \begin{aligned}解：4x+4.8&=15.2 \\ 4x&=10.4 \\ x&=2.6 \\ \end{aligned}$
$ \begin{aligned}解：\frac {2}{3}x&=\frac {5}{6} \\ x&=\frac {5}{4} \\ \end{aligned}$
$ \begin{aligned}解：\frac {5}{8}x&=\frac {5}{14}×21 \\ \frac {5}{8}x&=\frac {15}{2} \\ x&=12 \\ \end{aligned}$
$ \begin{aligned}解：\frac {2}{3}x&=\frac {2}{9}×21 \\ \frac {2}{3}x&=\frac {14}{3} \\ x&=7 \\ \end{aligned}$
=(772+128)−(317+283)
=900−600
=300
=(0.4×0.25)×12
=0.1×12
=1.2
=(3.8-0.9)×0.5
=2.9×0.5
=1.45
$=\frac {5}{12}×12+\frac {1}{19}×12+\frac {7}{19}$
$=5+(\frac {12}{19}+\frac {7}{19})$
$=5+1$
$=6$
=(127-26-1)×0.75
=100×0.75
=75
$ =1-\frac {1}{2}+\frac {1}{2}-\frac {1}{3}+\frac {1}{3}-\frac {1}{4}+\frac {1}{4}-\frac {1}{5}+\frac {1}{5}-\frac {1}{6}+\frac {1}{6}-\frac {1}{7}$
$=1-\frac {1}{7}$
$=\frac {6}{7}$
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