解比例。
$3:8 = x:16$
$\frac{25}{4} = \frac{5}{x}$
$\frac{5}{20} = \frac{15}{x}$
$x:\frac{3}{4} = \frac{1}{3}:\frac{1}{6}$
$x:25 = 1.2:25$
$\frac{1}{4}:\frac{1}{2} = \frac{1}{6}:x$
$2:6 = 3:x$
$22:11 = x:5$
$32:x = 8:2$
$x:25 = 4:5$
$\frac{x}{16} = \frac{3}{8}$
$\frac{6.4 + 1.5}{x} = \frac{5}{5×4}$

解：8x = 3×16
8x = 48
x = 6
解：25x = 4×5
25x = 20
x = $\frac{4}{5}$
解：5x = 20×15
5x = 300
x = 60
解：$\frac{1}{6}x = \frac{3}{4}×\frac{1}{3}$
$\frac{1}{6}x = \frac{1}{4}$
x = $\frac{1}{4}÷\frac{1}{6}$
x = $\frac{3}{2}$
解：25x = 25×1.2
x = 1.2
解：$\frac{1}{4}x = \frac{1}{2}×\frac{1}{6}$
$\frac{1}{4}x = \frac{1}{12}$
x = $\frac{1}{12}÷\frac{1}{4}$
x = $\frac{1}{3}$
解：2x = 6×3
2x = 18
x = 9
解：11x = 22×5
11x = 110
x = 10
解：8x = 32×2
8x = 64
x = 8
解：5x = 25×4
5x = 100
x = 20
解：8x = 16×3
8x = 48
x = 6
解：5x = (6.4+1.5)×(5×4)
5x = 7.9×20
5x = 158
x = 31.6