3. Решите пропорцию: a) $$\frac{x}{17} = \frac{4}{8}$$; б) $$\frac{13}{24} = \frac{x}{36}$$

a) $$\frac{x}{17} = \frac{4}{8}$$

$$x = \frac{4 \cdot 17}{8} = \frac{17}{2} = 8.5$$

б) $$\frac{13}{24} = \frac{x}{36}$$

$$x = \frac{13 \cdot 36}{24} = \frac{13 \cdot 3}{2} = \frac{39}{2} = 19.5$$