Помогите пожалуйста материал сложный

1) 1/х + 1/(1 2/7 х) = 4/9 |* 1 2/7 х
1 2/7 +1 = 4/7 х
2 2/7 = 4/7 
х = 2 2/7: 4/7 = 16/7 : 4/7 = 16/7* 7/4 = 4
х = 4
2) 2/(1 3/5 х) - 1/х = 1/12 |* 1 3/5 х
2 - 1 3/5 = 1/12*1 3/5 х
2/5 = 1/12 * 8/5 х
2/5 = 2/15 х
х = 2/5 : 2/15 = 2/5*15/2 = 3
х = 3
3) 2/(1 1/3 х) - 1/х = 1/4 |* 1 1/3 х
2 - 1 1/3 = 1/4 * 1 1/3 х
2/3 = 1/4 * 4/3 х
2/3 = 1/3 х
х= 2/3 : 1/3= 2/3 * 3/1 = 2
х = 2