21. 12/16 = x/32

Решение:

1. \[ \frac{12}{16} = \frac{x}{32} \]
2. \[ x = \frac{12 \times 32}{16} \]
3. \[ x = 12 \times 2 \]
4. \[ x = 24 \]

Ответ: x = 24