第86页 - 亮点给力提优课时作业本五年级数学江苏版

B

$\begin{aligned}解：x&=\frac {1}{2}+\frac {3}{14}+\frac {4}{7}\\x&=\frac {5}{7}+\frac {4}{7}\\x&=\frac {9}{7}\end{aligned}$

$\begin{aligned}解：x&=1+\frac {1}{3}-\frac {3}{4}\\x&=\frac {4}{3}-\frac {3}{4}\\x&=\frac {7}{12}\end{aligned}$

$=(\frac {13}{11}-\frac {1}{11})-(\frac {3}{5}+\frac {2}{5})$

$=\frac {12}{11}-1$

$=\frac {1}{11}$

$=(\frac {5}{4}-\frac {1}{4})-(\frac {2}{7}+\frac {5}{7})$

$=1-1$

$=0$

$=(\frac {11}{8}-\frac {5}{8})+(\frac {3}{7}+\frac {4}{7})$

$=\frac {3}{4}+1$

$=\frac {7}{4}$

$=(\frac {1}{6}+\frac {5}{6})+(\frac {7}{8}-\frac {1}{8})$

$=1+\frac {3}{4}$

$=1 \frac {3}{4}$

$\frac 35+\frac 12-1=\frac {1}{10}$

答：两种都订阅的占全班人数的$\frac {1}{10}。$

$1-\frac 34=\frac 14($杯)

$\frac 14+\frac 13=\frac {7}{12}($杯)

$1-\frac 14-\frac {7}{12}=\frac 16($杯)

答：溢出来的水是$\frac 16$杯。

$\frac 78+(0.75-\frac 13)=\frac {31}{24}($吨)

答：这时两个茶园的茶叶相差$\frac {31}{24}$吨。

$\frac {14}{3}+\frac {35}{6}+\frac {15}{2}-15=3 ($千克)

$3÷3=1\ (千克)$

$答：一个木箱重1千克。$