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想一想 准确计算。
$\frac {14}{15}÷\frac {3}{10}=$$\frac{28}{9}$ $\frac {8}{9}÷\frac {4}{15}=$$\frac{10}{3}$ $\frac {9}{10}×\frac {2}{3}=$$\frac{3}{5}$ $\frac {1}{9}×63=$7
$\frac {5}{48}÷\frac {1}{6}=$$\frac{5}{8}$ $\frac {12}{35}÷\frac {8}{21}=$$\frac{9}{10}$ $15÷\frac {10}{13}=$$\frac{39}{2}$ $1-\frac {4}{13}=$$\frac{9}{13}$

答案： $\frac{14}{15}÷\frac{3}{10}=\frac{14}{15}×\frac{10}{3}=\frac{28}{9}$
$\frac{8}{9}÷\frac{4}{15}=\frac{8}{9}×\frac{15}{4}=\frac{10}{3}$
$\frac{9}{10}×\frac{2}{3}=\frac{3}{5}$
$\frac{1}{9}×63=7$
$\frac{5}{48}÷\frac{1}{6}=\frac{5}{48}×6=\frac{5}{8}$
$\frac{12}{35}÷\frac{8}{21}=\frac{12}{35}×\frac{21}{8}=\frac{9}{10}$
$15÷\frac{10}{13}=15×\frac{13}{10}=\frac{39}{2}$
$1-\frac{4}{13}=\frac{9}{13}$

1. 计算下列各题。
$4×(\frac {3}{16}+\frac {3}{4})$ $\frac {7}{9}×\frac {3}{10}+\frac {7}{10}×\frac {7}{9}$ $\frac {3}{5}×6-\frac {3}{5}$
$\frac {13}{18}×19-\frac {13}{18}$ $(\frac {1}{3}-\frac {1}{4})÷\frac {1}{2}+\frac {5}{6}$ $20÷\frac {8}{9}÷\frac {3}{4}$

答案： 解析：本题主要考查分数的混合运算，包括乘法分配律、结合律等的应用。
答案：
1. $4 × \left( \frac{3}{16} + \frac{3}{4} \right)$
$= 4 × \frac{3}{16} + 4 × \frac{3}{4}$
$= \frac{3}{4} + 3$
$= 3\frac{3}{4}$
2. $\frac{7}{9} × \frac{3}{10} + \frac{7}{10} × \frac{7}{9}$
$= \frac{7}{9} × \left( \frac{3}{10} + \frac{7}{10} \right)$
$= \frac{7}{9} × 1$
$= \frac{7}{9}$
3. $\frac{3}{5} × 6 - \frac{3}{5}$
$= \frac{3}{5} × (6 - 1)$
$= \frac{3}{5} × 5$
$= 3$
4. $\frac{13}{18} × 19 - \frac{13}{18}$
$= \frac{13}{18} × (19 - 1)$
$= \frac{13}{18} × 18$
$= 13$
5. $\left( \frac{1}{3} - \frac{1}{4} \right) ÷ \frac{1}{2} + \frac{5}{6}$
$= \frac{1}{12} × 2 + \frac{5}{6}$
$= \frac{1}{6} + \frac{5}{6}$
$= 1$
6. $20 ÷ \frac{8}{9} ÷ \frac{3}{4}$
$= 20 × \frac{9}{8} × \frac{4}{3}$
$= \frac{180}{8} × \frac{4}{3}$
$= \frac{45}{2} × \frac{4}{3}$
$= 30$

2. 列式计算,能简算的要简算。
$\frac {5}{6}÷\frac {2}{3}÷\frac {5}{6}$ $\frac {18}{35}÷0.6×\frac {3}{2}$ $\frac {4}{7}÷(\frac {13}{14}+\frac {15}{16}÷\frac {5}{8})$

答案： $\frac{5}{6}÷\frac{2}{3}÷\frac{5}{6}$
$=\frac{5}{6}×\frac{3}{2}×\frac{6}{5}$
$=(\frac{5}{6}×\frac{6}{5})×\frac{3}{2}$
$=1×\frac{3}{2}$
$=\frac{3}{2}$
$\frac{18}{35}÷0.6×\frac{3}{2}$
$=\frac{18}{35}÷\frac{3}{5}×\frac{3}{2}$
$=\frac{18}{35}×\frac{5}{3}×\frac{3}{2}$
$=\frac{18}{35}×(\frac{5}{3}×\frac{3}{2})$
$=\frac{18}{35}×\frac{5}{2}$
$=\frac{9}{7}$
$\frac{4}{7}÷(\frac{13}{14}+\frac{15}{16}÷\frac{5}{8})$
$=\frac{4}{7}÷(\frac{13}{14}+\frac{15}{16}×\frac{8}{5})$
$=\frac{4}{7}÷(\frac{13}{14}+\frac{3}{2})$
$=\frac{4}{7}÷(\frac{13}{14}+\frac{21}{14})$
$=\frac{4}{7}÷\frac{34}{14}$
$=\frac{4}{7}×\frac{14}{34}$
$=\frac{4}{17}$