一、口算。
402 - 356 =
$\frac{5}{7} ÷ \frac{10}{21} =$
80% × 40% × 50% =
$\frac{3}{8} × \frac{32}{9} =$
$\frac{3}{8} ÷ \frac{5}{64} =$
0.4 × 6 ÷ 0.4 × 6 =
0.39 + 0.11 =
125 × 0.8 =
$6 ÷ (\frac{1}{2} + \frac{1}{3}) =$
$\frac{6}{5} ÷ \frac{18}{25} =$
298 + 437 =
$1 ÷ \frac{1}{3} × 1 ÷ \frac{1}{3} =$
2.17 - 1.29 =
$\frac{5}{18} × \frac{4}{7} =$
3.2 × 2.5 × 0.4 =
2.43 ÷ 0.3 =
440 ÷ 20 =
$4 - \frac{5}{4} - 1.75 =$
1 - 45% =
50% × 90% =
$12 × (\frac{1}{2} + \frac{1}{4}) =$

一、46 $\dfrac{3}{2}$ 0.16
$\dfrac{4}{3}$ $\dfrac{24}{5}$ 36
0.5 100 $\dfrac{36}{5}$
$\dfrac{5}{3}$ 735 9
0.88 $\dfrac{10}{63}$ 3.2
8.1 22 1
0.55 0.45 9

二、解方程或比例。
$\frac{3}{4} : x = 12 : 0.3$
$\frac{10}{3} : x = \frac{4}{9} : \frac{4}{3}$
$\frac{5}{8}x - 25\%x = \frac{3}{2}$
$(x - 3.6) × 4 = 28.8$
$\frac{1.4}{x} = 7 : 1.5$
$5x - 8 × 25\% = \frac{1}{12}$

二、$x=\dfrac{3}{160}$ $x=10$ $x=4$
$x=10.8$ $x=0.3$ $x=\dfrac{5}{12}$