Вычислите: 1) х-2/3=1/18 2) 1/12+х=3/4 + 1/6 3) 19/20-х=1/4 4) х+3/20=7/10+1/4

1) х - 2/3 = 1/18;

х = 1/18 + 2/3;

х = 1/18 + 2/3 * 6/6;

х = 1/18 + 12/18;

х = 13/18;

2) 1/12 + х = 3/4 + 1/6;

х = 3/4 + 1/6 + 1/12;

х = 3/4 * 3/3 + 1/6 * 2/2 + 1/12;

х = 9/12 + 2/12 + 1/12;

х = 12/12;

х = 12 : 12;

х = 1;

3) 19/20 - х = 1/4;

х = 19/20 - 1/4;

х = 19/20 - 1/4 * 5/5;

х = 19/20 - 5/20;

х = 14/20;

х = (14 : 2) / (20 : 2);

х = 7/10.

4) х + 3/20 = 7/10 + 1/4;

х = 7/10 + 1/4 - 3/20;

х = 7/10 * 2/2 + 1/4 * 5/5 - 3/20;

х = 14/20 + 5/20 - 3/20;

х = 19/20 - 3/20;

х = 16/20;

х = (16 : 4) / (20 : 4);

х = 4/5;