3х + 8 1/6 = 12,2
3х = 12 2/10 - 8 1/6
3х = 4 1/6
х = 25/6 : 3 = 25/18
х = 1 7/18
-----------------------------------
10,5 - 4х = 2 1/3
4х = 10 5/10 - 2 1/3
4х = 8 1/6
х = 49/6 : 4 = 49/24
х = 2 1/24
------------------------------------
х : 0,7 = 2/35
х = 2/35 * 7/10
х = 14/350
х = 7/175
---------------------------------
2,5х = 1/11
х = 1/11 : 2 1/2
х = 1/11 : 5/2
х = 2/55