X+ 9/20=3/4,25/36-x=5/18,x-13/20=1/10

1) X + 9/20 = 3/4;

Х = 3/4 - 9/20 = (3 * 5)/(4 * 5) - 9/20 = 15/20 - 9/20 = (15 - 9)/20 = 6/20 = 3/10 = 0,3.

Ответ: Х = 0,3.

2) 25/36 - x = 5/18;

х = 25/36 - 5/18 = 25/36 - (5 * 2)/(18 * 2) = 25/36 - 10/36 = (25 - 10)/36 = 15/36 = 5/12.

Ответ: х = 5/12.

3) x - 13/20 = 1/10;

х = 13/20 + 1/10 = 13/20 + 2/20 = (13 + 2)/20 = 15/20 = 3/4.

Ответ: х = 3/4.