1. 直接写出得数。
$\frac{1}{4}÷\frac{1}{6}= $
$\frac{5}{7}×\frac{2}{5}= $
$15÷\frac{3}{4}= $
$\frac{3}{4}×\frac{2}{3}= $
$\frac{1}{4}+\frac{1}{8}= $
$\frac{2}{3}-\frac{1}{2}= $
$\frac{5}{26}×39= $
$0÷\frac{5}{7}= $

$1\frac{1}{2}$
$\frac{2}{7}$
20
$\frac{1}{2}$
$\frac{3}{8}$
$\frac{1}{6}$
$7\frac{1}{2}$
0

2. 看图列式计算。

$​10 ×\frac {4}{5} ×\frac {5}{8}=5(​$吨​)​
$​36 ×\frac {2}{3} ×\frac {3}{4}=18( ​$个​)​

3. 解方程。
$\frac{2}{3}x+\frac{1}{6}x= \frac{1}{4}$
$x-\frac{7}{9}x= \frac{2}{15}$
$\frac{3}{5}x+20= 50$

$\begin {aligned}$解：$\frac {5}{6}x&=\frac {1}{4}\\x &=\frac {3}{10}\end {aligned}$
$\begin {aligned}$解：$\frac {2}{9}x&=\frac {2}{15}\\x &=\frac {3}{5}\end {aligned}$
$\begin {aligned}$解：$\frac {3}{5}x&=50-20\\\frac {3}{5}x&=30\\x &=50\end {aligned}$

4. 用简便方法计算。
$\frac{7}{13}×\frac{2}{5}-\frac{2}{13}×\frac{2}{5}$
$24-24×\frac{18}{19}$
$\frac{5}{7}÷\frac{1}{4}+\frac{5}{7}÷\frac{3}{4}$

$​=(\frac {7}{13}-\frac {2}{13}) ×\frac {2}{5}​$
$​=\frac {5}{13} ×\frac {2}{5}​$
$​=\frac {2}{13}​$
$​=24 ×(1-\frac {18}{19})​$
$​=24 ×\frac {1}{19}​$
$​=\frac {24}{19}​$
$​=\frac {5}{7} ×4+\frac {5}{7} ×\frac {4}{3}​$
$​=\frac {5}{7} ×(4+\frac {4}{3})​$
$​=\frac {5}{7} ×\frac {16}{3}​$
$​=\frac {80}{21}​$