Question

13．下面各題，怎樣算簡便就怎樣算．
$\frac{3}{8}$÷12×$\frac{16}{5}$
$（\frac{1}{3}+\frac{1}{6}）÷\frac{1}{18}$
$\frac{7}{8}$-（1-$\frac{1}{4}$）÷6
$\frac{4}{5}×\frac{2}{3}+\frac{1}{5}÷\frac{3}{4}$．

Answer 1

分析 ①先把除法變乘法，再根據(jù)乘法的交換律結合律簡算；
②先把乘法變除法，再根據(jù)乘法的分配律簡算；
③先算括號里減法，再把除法變乘法，最后算減法．
④把除法變乘法，根據(jù)乘法的性質，原式變?yōu)椋?\frac{4}{5}$×$\frac{2}{3}$+$\frac{4}{5}$×$\frac{1}{3}$，再根據(jù)乘法的分配律簡算．

解答 解：①$\frac{3}{8}$÷12×$\frac{16}{5}$
=$\frac{3}{8}$×$\frac{16}{5}$×$\frac{1}{12}$
=$\frac{6}{5}$×$\frac{1}{12}$
=$\frac{1}{10}$

②$（\frac{1}{3}+\frac{1}{6}）÷\frac{1}{18}$
=（$\frac{1}{3}$+$\frac{1}{6}$）×18
=$\frac{1}{3}$×18+$\frac{1}{6}$×18
=6+3
=9

③$\frac{7}{8}$-（1-$\frac{1}{4}$）÷6
=$\frac{7}{8}$-$\frac{3}{4}$×$\frac{1}{6}$
=$\frac{7}{8}$-$\frac{1}{8}$
=$\frac{3}{4}$

④④$\frac{4}{5}×\frac{2}{3}+\frac{1}{5}÷\frac{3}{4}$
=$\frac{4}{5}$×$\frac{2}{3}$+$\frac{1}{5}$×$\frac{4}{3}$
=$\frac{4}{5}$×$\frac{2}{3}$+$\frac{4}{5}$×$\frac{1}{3}$
=$\frac{4}{5}$×（$\frac{2}{3}$+$\frac{1}{3}$）
=$\frac{4}{5}$

點評 此題主要考查的是分數(shù)的簡便運算和分數(shù)的四則混合運算．