1) 4(7-5x)-(12-20x);
2) 2(3x-y)-(5x-2y);
3) 6(x+2y)-3(2x+y);
4) 5(4x+y)–2(x,y).​

1) 16

2) x

3) 9y

4) 18x + 7y

Пошаговое объяснение:

1) 4(7 - 5x) - (12 - 20x) = 28 - 20x - 12 + 20x = 28 - 12 = 16

2) 2(3x - y) - (5x - 2y) = 6x - 2y - 5x + 2y = 6x - 5x = x

3) 6(x + 2y) - 3(2x + y) = 6x + 12y - 6x - 3y = 12y - 3y = 9y

4) 4) 5(4x + y) - 2(x - y) = 20x + 5y - 2x + 2y = 18x + 7y