1. 直接写出得数。
$2 - \frac{3}{5} =$ $\frac{3}{5} ÷ \frac{5}{3} =$ $\frac{3}{14} ÷ \frac{1}{14} =$
$26 × \frac{1}{2} =$ $\frac{3}{8} ÷ \frac{9}{32} =$ $24 ÷ \frac{2}{3} =$
$0.25 × 100 =$ $3.4 - 2.8 =$ $0.6 - 0.37 =$

$2 - \frac{3}{5} = \frac{10}{5} - \frac{3}{5} = \frac{7}{5}$
$\frac{3}{5} ÷ \frac{5}{3} = \frac{3}{5} × \frac{3}{5} = \frac{9}{25}$
$\frac{3}{14} ÷ \frac{1}{14} = \frac{3}{14} × 14 = 3$
$26 × \frac{1}{2} = 13$
$\frac{3}{8} ÷ \frac{9}{32} = \frac{3}{8} × \frac{32}{9} = \frac{4}{3}$
$24 ÷ \frac{2}{3} = 24 × \frac{3}{2} = 36$
$0.25 × 100 = 25$
$3.4 - 2.8 = 0.6$
$0.6 - 0.37 = 0.23$

2. 脱式计算。（能简算的要简算）
$3.6 × 125 + 125 × 4.4$ $400.18 - 174.56 - 25.44$
$322.84 - 69 - 222.84$ $121.45 + 37 - 21.45$

$3.6 × 125 + 125 × 4.4$
$=125×(3.6+4.4)$
$=125×8$
$=1000$
$400.18 - 174.56 - 25.44$
$=400.18-(174.56+25.44)$
$=400.18-200$
$=200.18$
$322.84 - 69 - 222.84$
$=322.84-222.84-69$
$=100-69$
$=31$
$121.45 + 37 - 21.45$
$=121.45-21.45+37$
$=100+37$
$=137$

3. 解方程。
$(1 - \frac{1}{5})x = \frac{16}{25}$ $x - \frac{2}{5}x = \frac{1}{2}$ $\frac{9}{3.6} = \frac{5}{x}$

第一个方程
解：
$(1 - \frac{1}{5})x = \frac{16}{25}$
$\frac{4}{5}x = \frac{16}{25}$
$x = \frac{16}{25} ÷ \frac{4}{5}$
$x = \frac{16}{25} × \frac{5}{4}$
$x = \frac{4}{5}$
第二个方程
解：
$x - \frac{2}{5}x = \frac{1}{2}$
$\frac{3}{5}x = \frac{1}{2}$
$x = \frac{1}{2} ÷ \frac{3}{5}$
$x = \frac{1}{2} × \frac{5}{3}$
$x = \frac{5}{6}$
第三个方程
解：
$\frac{9}{3.6} = \frac{5}{x}$
$9x = 3.6 × 5$
$9x = 18$
$x = 18 ÷ 9$
$x = 2$

4. 列竖式计算并验算。
$5.92 ÷ 1.6 =$ $0.63 ÷ 0.15 =$ $140.4 ÷ 18 =$

$5.92 ÷ 1.6 = 3.7$
计算竖式：
3.7
16)59.2
48
---
112
112
---
0
验算：
3.7
× 1.6
-----
222
37
-----
5.92
$0.63 ÷ 0.15 = 4.2$
计算竖式：
4.2
15)63.0
60
---
30
30
---
0
验算：
4.2
×0.15
-----
210
42
-----
0.630
$140.4 ÷ 18 = 7.8$
计算竖式：
7.8
18)140.4
126
---
144
144
---
0
验算：
7.8
× 18
-----
624
78
-----
140.4