一、口算。
拍照批改
$\frac {2}{3}-\frac {2}{15}=$ $\frac {4}{5}÷\frac {6}{25}=$ $24×(\frac {1}{4}-\frac {1}{6})=$
$\frac {3}{4}+\frac {2}{7}=$ $\frac {15}{91}×\frac {13}{20}=$ $\frac {2}{5}+\frac {3}{5}×2=$
$0.75×\frac {1}{2}=$ $78\% ÷\frac {13}{15}=$ $1.8-0.25-75\% =$
$9.1÷0.7=$ $78-0.98=$ $(5-0.8)×0.2=$
$\frac {7}{30}+\frac {3}{8}=$ $1.5×50\% =$ $\frac {11}{12}-\frac {5}{6}+\frac {1}{12}=$
$32×125\% =$ $8.1÷0.03=$ $25÷(\frac {1}{2}+\frac {1}{3})=$
$12-\frac {3}{8}=$ $\frac {5}{6}÷5\% =$ $\frac {15}{7}-(\frac {3}{4}+\frac {8}{7})=$

$\frac{8}{15}$ $\frac{10}{3}$ 2 $\frac{29}{28}$ $\frac{3}{28}$ $\frac{8}{5}$ $\frac{3}{8}$ 0.9 0.8 13 77.02 0.84 $\frac{73}{120}$ 0.75 $\frac{1}{6}$ 40 270 30 $11\frac{5}{8}$ $\frac{50}{3}$ $\frac{1}{4}$

二、计算下面各图形的表面积和体积。

表面积：$\frac{5}{3}×\frac{5}{3}×6 = \frac{50}{3}(cm^{2})$ 体积：$\frac{5}{3}×\frac{5}{3}×\frac{5}{3} = \frac{125}{27}(cm^{3})$ 表面积：$3×3×6 - 1×1×2 + 1×3×4 = 64(cm^{2})$ 体积：$3×3×3 - 1×1×3 = 24(cm^{3})$