2(x-3)+3(x+1)=12 7(x-1)-2(2x+5)=2x-10 3(2x-2/3)-2(x-7,5)=2(x+7,5)

Решим уравнения:

1) 2 * (x - 3) + 3 * (x + 1) = 12; 

2 * x - 6 + 3 * x + 3 = 12;

5 * x - 3 = 12;

5 * x = 12 + 3;

5 * x = 15;

x= 15/5;

x = 3;

2) 7 * (x - 1) - 2 * (2 * x + 5) = 2 * x - 10; 

7 * x - 7 - 4 * x - 10 = 2 * x - 10;

3 * x - 17 = 2 * x - 10;

3 * x - 2 * x = -10 + 17;

x = 7;

3) 3 * (2 * x - 2/3) - 2 * (x - 7,5) = 2 * (x + 7,5); 

6 * x - 3 * 2/3 - 2 * x + 2 * 7.5 = 2 * x + 2 * 7.5; 

6 * x - 2 - 2 * x + 15 = 2 * x + 15; 

6 * x - 2 - 2 * x = 2 * x; 

4 * x - 2 = 2 * x; 

4 * x - 2 * x = 2; 

2 * x = 2; 

x = 2/2; 

x = 1.