решите неравенство: 6 (3+5y) - (2+7y) <=5 (4+3y)

6 * (3 + 5 * y) - (2 + 7 * y) < = 5 * (4 + 3 * y);

Раскроем скобки.

6 * 3 + 5 * 6 * y - 2 - 7 * y < = 5 * 4 + 5 * 3 * y;

18 + 30 * y - 2 - 7 * y < = 20 + 15 * y;

(18 - 2) + (30 * y - 7 * y) < = 20 + 15 * y;

16 + y * (30 - 7) < = 20 + 15 * y;

16 + y * 21 < = 20 + 15 * y;

21 * y + 16 < = 15 * y + 20;

21 * y - 15 * y < = 20 - 16;

y * (21 - 15) < = 4;

y * 6 < = 4;

6 * y < = 4;

y < = 4/6;

y < = 2/3;

Ответ: y < = 2/3.