一、将百分数改写成整数或小数(分数),将整数或小数(分数)改写成百分数。
$17.8\% =$
$500\% =$
$85\% = \frac{}{}$
$13.5\% = \frac{}{}$
$0.4\% =$
$1.2\% = \frac{}{}$
$360\% = \frac{}{}$
$150\% =$
$175\% = \frac{}{}$
$0.425= $$\% $
$\frac {1}{3}\approx $$\% $
$8.25= $$\% $
$30= $$\% $
$\frac {13}{2}= $$\% $
$\frac {11}{16}= $$\% $
$0.08= $$\% $
$\frac {27}{40}= $$\% $
$0.404= $$\% $

解析：本题考查百分数与小数和分数的相互改写。
答案：
$17.8\% = 0.178$；
$500\% = 5$；
$85\% = \frac{85}{100}$；
$13.5\% = \frac{135}{1000}=\frac{27}{200}$；
$0.4\% = 0.004$；
$1.2\% = \frac{12}{1000}=\frac{3}{250}$；
$360\% = \frac{360}{100}=\frac{18}{5}$；
$150\% = 1.5$；
$175\% = \frac{175}{100}=\frac{7}{4}$；
$0.425 = 42.5\%$；
$\frac{1}{3} \approx 33.3\%$；
$8.25 = 825\%$；
$30 = 3000\%$；
$\frac{13}{2} = 6.5 = 650\%$；
$\frac{11}{16} = 0.6875 = 68.75\%$；
$0.08 = 8\%$；
$\frac{27}{40} = 0.675 = 67.5\%$；
$0.404 = 40.4\%$。

二、解方程。
$x÷\frac {5}{8}= \frac {10}{17}$
$6+\frac {7}{10}x= 10$
$\frac {2}{3}x-\frac {3}{5}x= 12$
$4x+\frac {1}{2}x= 9$
$4x+\frac {1}{9}= 5$
$\frac {5}{8}x= \frac {2}{5}+\frac {3}{5}$
$(1-\frac {1}{2})x= 14$
$2x-\frac {2}{7}x= \frac {2}{3}$
$\frac {5}{9}×\frac {9}{2}+\frac {1}{3}x= \frac {11}{4}$

二、解方程。
1.
解：$x ÷ \frac{5}{8} = \frac{10}{17}$
$x = \frac{10}{17} × \frac{5}{8}$
$x = \frac{25}{68}$
2.
解：$6 + \frac{7}{10}x = 10$
$\frac{7}{10}x = 4$
$x = \frac{40}{7}$
3.
解：$\frac{2}{3}x - \frac{3}{5}x = 12$
$\frac{1}{15}x = 12$
$x = 180$
4.
解：$4x + \frac{1}{2}x = 9$
$\frac{9}{2}x = 9$
$x = 2$
5.
解：$4x + \frac{1}{9} = 5$
$4x = \frac{44}{9}$
$x = \frac{11}{9}$
6.
解：$\frac{5}{8}x = \frac{2}{5} + \frac{3}{5}$
$\frac{5}{8}x = 1$
$x = \frac{8}{5}$
7.
解：$(1 - \frac{1}{2})x = 14$
$\frac{1}{2}x = 14$
$x = 28$
8.
解：$2x - \frac{2}{7}x = \frac{2}{3}$
$\frac{12}{7}x = \frac{2}{3}$
$x = \frac{7}{18}$
9.
解：$\frac{5}{9} × \frac{9}{2} + \frac{1}{3}x = \frac{11}{4}$
$\frac{5}{2} + \frac{1}{3}x = \frac{11}{4}$
$\frac{1}{3}x = \frac{1}{4}$
$x = \frac{3}{4}$