四、计算下面各题,能用简便算法的就用简便算法。(每题3分,共27分)
$\frac{5}{7}×21×\frac{3}{10}$
$(\frac{1}{4}-\frac{1}{6})×24$
$\frac{7}{9}÷\frac{11}{5}+\frac{2}{9}×\frac{5}{11}$
$\frac{9}{26}÷\frac{8}{13}×\frac{98}{27}$
$\frac{7}{9}+\frac{2}{9}×\frac{3}{4}$
$35÷\frac{7}{8}×(1-\frac{2}{7})$
$\frac{1}{17}÷7+\frac{1}{7}×\frac{6}{17}$
$(15-14×\frac{6}{7})×\frac{8}{21}$
$10.8÷[32×(1-\frac{5}{8})]$

1. $\frac{9}{2}$
2. $2$
3. $\frac{5}{11}$
4. $\frac{49}{24}$
5. $\frac{17}{18}$
6. $\frac{200}{7}$
7. $\frac{1}{17}$
8. $\frac{8}{7}$
9. $\frac{9}{10}$

五、看图列式计算。(每题5分,共10分)
1.
运走$\frac{8}{25}$t
共有？t煤
2.
钢笔: 15元
圆珠笔:
铅笔: ？元

1. $\frac{8}{25}÷\frac{1}{5}=\frac{8}{5}(\mathrm{t})$
2. $15×\frac{2}{5}×\frac{1}{3}=2(\mathrm{元})$

计算下面各题。(每题2.5分,共5分)
1. $60\frac{4}{5}÷19$
2. $157\frac{1}{15}÷31$

1. $60\frac{4}{5}÷19=(57+3\frac{4}{5})÷19=(57+\frac{19}{5})×\frac{1}{19}=57×\frac{1}{19}+\frac{19}{5}×\frac{1}{19}=3+\frac{1}{5}=3\frac{1}{5}$
2. $157\frac{1}{15}÷31=(155+2\frac{1}{15})÷31=(155+\frac{31}{15})×\frac{1}{31}=155×\frac{1}{31}+\frac{31}{15}×\frac{1}{31}=5+\frac{1}{15}=5\frac{1}{15}$