X-1/2=3/4x; 1 4/5y=y+4; 3/4y-2/3=7/12y

1) х - 1/2 = 3/4x;х - 3/4х = 1/2;1/4х = 1/2;х = 2.2) 1 4/5y = y + 4;((1 * 5 + 4)/5)у - у = 4;4/5у = 4;у = 5.3) 3/4y - 2/3 = 7/12y;3/4у - 7/12у = 2/3;(3 * 3)/(4 * 3)у- 7/12у = 2/3;9/12у - 7/12у = 2/3;2/12у = 2/3;у = 2/3 : 2/12 = 2/3 * 12/2 = (1 * 4/(1 * 1);х = 4.