5. Реши уравнения.

1) \( x \cdot 9 = 810 \), \( x = \frac{810}{9} = 90 \). 2) \( x \div 8 = 280 \div 4 \), \( x = 8 \cdot (280 \div 4) = 8 \cdot 70 = 560 \). 3) \( 52 \div x = 193 \div 16 \), \( x = \frac{52 \cdot 16}{193} = \frac{832}{193} \approx 4,31 \).