1) (х - 2 3/7) + 4 5/21 = 1 5/42
х - 2 3/7 = 1 5/42 - 4 5/21 = 47/42 - 89/21 = (47-178)/42 = -131/42
х = -131/42 + 2 3/7 = -131/42 + 17/7 = (-131+102)/42 = -29/42
2) 22 - (х - 3 3/4) = 28
х - 3 3/4 = 22 - 28 = -6
х = -6 + 3 3/4 = -2 1/4
3) (х - 5 3/8) - 2 7/16 = -11 3/4
х - 5 3/8 = -11 3/4 + 2 7/16 = -47/4 + 39/16 = (-188+39)/16 = -149/16
х = -149/16 + 5 3/8 = -149/16 + 43/8 = (-149+86)/16 = -63/16 = -3 15/16
4) (13 2/9 + х) - 4 5/11 = 22 5/18
13 2/9 - х = 22 5/18 + 4 5/12 = 22+4 + (5/18+5/12) = 26 + (10+15)/36 = 26 25/36
х = 26 25/36 - 13 2/9 = 26-13 + (25/36 - 2/9) = 13 + (25-8)/36 = 13 17/36