191. Решите уравнения: а) 128 : 4x = 128; б) 280 : 15x = 45 : 280; в) 12x : 350 = 350 : 48; г) 29x : 430 = 58 : 430.

Решение:

1. а) 128 : 4x = 128
   \( 4x = 128 : 128 \)
   \( 4x = 1 \)
   \( x = 1 : 4 \)
   \( x = 0.25 \)
2. б) 280 : 15x = 45 : 280
   \( 15x = 280 \cdot \frac{280}{45} \)
   \( 15x = \frac{78400}{45} \)
   \( x = \frac{78400}{45 \cdot 15} \)
   \( x = \frac{78400}{675} \)
   \( x \approx 116.15 \)
3. в) 12x : 350 = 350 : 48
   \( 12x = \frac{350 \cdot 350}{48} \)
   \( 12x = \frac{122500}{48} \)
   \( x = \frac{122500}{48 \cdot 12} \)
   \( x = \frac{122500}{576} \)
   \( x \approx 212.67 \)
4. г) 29x : 430 = 58 : 430
   \( 29x = 430 \cdot \frac{58}{430} \)
   \( 29x = 58 \)
   \( x = 58 : 29 \)
   \( x = 2 \)