一、口算。
拍照批改
$\frac {5}{8}÷\frac {15}{16}=$ $\frac {5}{6}×\frac {2}{5}=$ $\frac {4}{9}-\frac {2}{7}+\frac {5}{9}=$
$25×40\% =$ $\frac {1}{2}-\frac {1}{6}=$ $(\frac {3}{4}+\frac {1}{5})×20=$
$\frac {5}{6}+\frac {3}{4}=$ $\frac {3}{8}×4=$ $\frac {5}{4}×8+8×\frac {1}{4}=$
$30\% ×30\% =$ $0.64÷8=$ $2.5-2.5÷5=$
$\frac {12}{7}-\frac {3}{2}=$ $72\% ÷0.9=$ $\frac {3}{4}÷3×\frac {3}{4}÷3=$
$\frac {13}{2}÷13\% =$ $35×20\% =$ $25×\frac {5}{6}×4=$
$\frac {4}{5}-65\% =$ $1.02+0.43=$ $2.7-0.49-0.51=$

$\frac{2}{3}$ $\frac{1}{3}$ $\frac{5}{7}$ 10 $\frac{1}{3}$ 19 $\frac{19}{12}$ $\frac{3}{2}$ 12 0.09 0.08 2 $\frac{3}{14}$ 0.8 $\frac{1}{16}$ 50 7 $\frac{250}{3}$ 0.15 1.45 1.7

二、解方程。
$x-\frac {2}{5}x= \frac {3}{10}$ $40\% x-30= 15$ $2x+20\% x= 3.3$
$3.6x÷15\% = 7.68$ $90\% (x-\frac {5}{12})= \frac {3}{4}$ $7.8×0.69+69\% x= 6.9$

$x = \frac{1}{2}$ $x = \frac{225}{2}$ $x = \frac{3}{2}$ $x = 0.32$ $x = \frac{5}{4}$ $x = 2.2$

1. $x-\frac{2}{5}x=\frac{3}{10}$
解：$\frac{3}{5}x=\frac{3}{10}$
$x=\frac{3}{10}÷\frac{3}{5}$
$x=\frac{1}{2}$
2. $40\%x - 30=15$
解：$0.4x=45$
$x=45÷0.4$
$x=\frac{225}{2}$
3. $2x + 20\%x=3.3$
解：$2.2x=3.3$
$x=3.3÷2.2$
$x=\frac{3}{2}$
4. $3.6x÷15\%=7.68$
解：$3.6x=7.68×0.15$
$3.6x=1.152$
$x=1.152÷3.6$
$x=0.32$
5. $90\%\left(x-\frac{5}{12}\right)=\frac{3}{4}$
解：$x-\frac{5}{12}=\frac{3}{4}÷0.9$
$x-\frac{5}{12}=\frac{5}{6}$
$x=\frac{5}{6}+\frac{5}{12}$
$x=\frac{5}{4}$
6. $7.8×0.69 + 69\%x=6.9$
解：$0.69x=6.9 - 7.8×0.69$
$0.69x=6.9 - 5.382$
$0.69x=1.518$
$x=1.518÷0.69$
$x=2.2$