Простое вещество 1) сера 2) вода 3) мел 4) хлорид натрия

1) x/3+x/2=x/6+1; 2x + 3x = x + 1; 4x = 1; x = 1/4;
2) y/2-y/8=y/4-1; 4y - y = 2y - 8; y = -8;
3) 5x/12-4x/15=x/20+1; 25x - 16x = 3x + 60; 6x = 60; x = 10
4) x/3-2x/9=x/6+1/2; 6x - 4x = 3x + 9; x = -9