Решите уравнения: (2/3x-4/5) * 15=8 (5/7-2/3y) * 21=1 2/3x+7/3x=18 7/12m+2/3m-1/4m=7

1) (2/3 * x - 4/5) * 15 = 8;

15 * 2/3 * x - 4/5 * 15 = 8;

10 * x - 12 = 8;

10 * х = 8 + 12;

х = 20/10 = 2;

2) (5/7 - 2/3 * y) * 21 = 1;

21 * 5/7 - 2/3 * y * 21 = 1;

15 - 14 * y = 1;

14 * у = 15 - 1;

у = 14/14 = 1;

3) 2/3 * x + 7/3 * x = 18;

(2 + 7) / 3 * х = 18;

3 * х = 18;

х = 18/3 = 6;

4) 7/12 * m + 2/3 * m - 1/4 * m = 7;

(7/12 + 2/3 - 1/4) * m = 7;

(7/12 + 8/12 - 3/12) * m = 7;

(7 + 8 - 3) / 12 * m = 7;

m = 7.