一、口算。
$2.5×50\% =$
$\frac{1}{10} - 3\% =$
$\frac{2}{5} ÷ \frac{6}{7} =$
$\frac{3}{5} ÷ \frac{3}{4} =$
$20×36\% =$
$\frac{1}{7} ÷ \frac{1}{7} =$
$10×10\% =$
$\frac{7}{5} - \frac{3}{4} =$
$\frac{7}{20} × \frac{5}{14} =$
$\frac{4}{5} + \frac{3}{7} =$
$\frac{3}{5} × \frac{5}{12} =$
$\frac{24}{25} ÷ \frac{4}{5} =$
$18\% × \frac{20}{9} =$
$\frac{7}{12} - \frac{4}{9} =$
$\frac{3}{4} - 20\% =$
$\frac{4}{9} × \frac{3}{20} =$
$45\% × \frac{2}{3} =$
$6 ÷ \frac{3}{8} =$
$\frac{5}{8} - \frac{5}{12} =$
$\frac{5}{6} × \frac{42}{55} =$
$\frac{7}{10} ÷ \frac{7}{13} =$

1.25
0.07
$\frac{7}{15}$
$\frac{4}{5}$
7.2
1
1
$\frac{13}{20}$
$\frac{1}{8}$
$\frac{43}{35}$
$\frac{1}{4}$
$\frac{6}{5}$
$\frac{2}{5}$
$\frac{5}{36}$
$\frac{11}{20}$
$\frac{1}{15}$
$\frac{3}{10}$
16
$\frac{5}{24}$
$\frac{7}{11}$
$\frac{13}{10}$

二、计算下面各图形中涂色部分的周长和面积。（单位：cm）
1.
2.

1. 周长:$3.14×30÷2+30+20×2=117.1(\mathrm{cm})$
面积:$30×20-3.14×(30÷2)^2÷2=246.75(\mathrm{cm}^2)$
2. 周长:$7×2+2×3.14×3÷4=18.71(\mathrm{cm})$
面积:$7×3-3.14×3^2÷4=13.935(\mathrm{cm}^2)$