1) х+(х+1,4)+(х+3/20)=4
х + х + 1,4 + х + 3/20 = 4
3х = 4 - 1,4 - 3/20
3х = 26/10 - 3/20
3х = 49/20
х = 49/20 : 3
х = 49/60
2) 5х+3/4х+0,25х=12,3 3/4х = 0,75х
6х = 12,3
х = 12,3 : 6
х = 2,05
3) 1 2/3х-х=2/3
2/3х = 2/3
х = 2/3 : 2/3
х = 1
4) 4,35х-х= 13 2/5
3,35х = 13,4
х = 13,4 : 3,35
х = 4