3. Реши уравнения. x - 12 = 56 x = 56+ 12 x=68 68-12=56 56=56 x+43=61 x=61-43 x=18 18+43=61 61=61 90-x = 78 x = 78+90 x=168 168-90=78 78=48

Решим уравнения.

1. 
   

   x - 12 = 56

   
   

   x = 56 + 12

   
   

   x = 68

   
   

   68 - 12 = 56

   
   

   56 = 56

   
   

   Ответ: x = 68

   
   


2. 
   

   x + 43 = 61

   
   

   x = 61 - 43

   
   

   x = 18

   
   

   18 + 43 = 61

   
   

   61 = 61

   
   

   Ответ: x = 18

   
   


3. 
   

   90 - x = 78

   
   

   x = 90 - 78

   
   

   x = 12

   
   

   90 - 12 = 78

   
   

   78 = 78

   
   

   Ответ: x = 12