一、口算。
拍照批改
$\frac {2}{5}-30\% =$ $0.1×30\% =$ $\frac {4}{5}÷10\% =$
$\frac {1}{2}-\frac {1}{5}=$ $2.5×2.4=$ $0.77+30\% =$
$72\% ×\frac {5}{9}=$ $1÷75\% =$ $50\% ×0.1=$
$3.9÷13\% =$ $1.5×20\% =$ $\frac {6}{7}÷\frac {10}{13}=$
$6×\frac {5}{12}=$ $\frac {3}{2}÷\frac {5}{2}=$ $\frac {8}{5}-\frac {9}{10}=$
$5÷1\% =$ $1-75\% =$ $40\% +1.8=$
$0.95-5\% =$ $\frac {2}{3}+\frac {1}{4}=$ $\frac {5}{12}×\frac {3}{20}=$

0.1 0.03 8 $\frac{3}{10}$ 6 1.07 $\frac{2}{5}$ $\frac{4}{3}$ 0.05 30 0.3 $\frac{39}{35}$ $\frac{5}{2}$ $\frac{3}{5}$ $\frac{7}{10}$ 500 0.25 2.2 0.9 $\frac{11}{12}$ $\frac{1}{16}$

$\frac{2}{5}-30\% = 0.4 - 0.3 = 0.1$
$0.1×30\% = 0.1×0.3 = 0.03$
$\frac{4}{5}÷10\% = 0.8÷0.1 = 8$
$\frac{1}{2}-\frac{1}{5} = \frac{5}{10}-\frac{2}{10} = \frac{3}{10}$
$2.5×2.4 = 2.5×4×0.6 = 10×0.6 = 6$
$0.77 + 30\% = 0.77 + 0.3 = 1.07$
$72\%×\frac{5}{9} = 0.72×\frac{5}{9} = 0.08×5 = 0.4 = \frac{2}{5}$
$1÷75\% = 1÷\frac{3}{4} = \frac{4}{3}$
$50\%×0.1 = 0.5×0.1 = 0.05$
$3.9÷13\% = 3.9÷0.13 = 30$
$1.5×20\% = 1.5×0.2 = 0.3$
$\frac{6}{7}÷\frac{10}{13} = \frac{6}{7}×\frac{13}{10} = \frac{39}{35}$
$6×\frac{5}{12} = \frac{5}{2}$
$\frac{3}{2}÷\frac{5}{2} = \frac{3}{2}×\frac{2}{5} = \frac{3}{5}$
$\frac{8}{5}-\frac{9}{10} = \frac{16}{10}-\frac{9}{10} = \frac{7}{10}$
$5÷1\% = 5÷0.01 = 500$
$1 - 75\% = 1 - 0.75 = 0.25$
$40\% + 1.8 = 0.4 + 1.8 = 2.2$
$0.95 - 5\% = 0.95 - 0.05 = 0.9$
$\frac{2}{3}+\frac{1}{4} = \frac{8}{12}+\frac{3}{12} = \frac{11}{12}$
$\frac{5}{12}×\frac{3}{20} = \frac{1}{16}$

二、计算下面各图形的表面积和体积。

表面积：$(8.5×6 + 8.5×4 + 6×4)×2 = 218(cm^{2})$ 体积：$8.5×6×4 = 204(cm^{3})$ 表面积：$[6×4 + 6×2 + 2×2 + 4×(2 + 2)]×2 = 112(m^{2})$ 体积：$6×4×2 + 2×4×2 = 64(m^{3})$