x -4.2 =4.6
x =4.6+4.2
x =8.8
76)x +75.2 /2 =49.6
x+75.2 =49.6 *2
x +75.2 =99.2
x =99.2 -75.2
x =24
77)a +b+c=123
a=b-1
c=b+1
123/3 =41 ; b =41
a =41-1 =40
c =41 +1 =42
40+41+42 =123
78) 3x =5.25
x =5.25 :3
x =1.75
79)x /2 +0.7 =8.2 numitor comun 2
x +0.14 =16.4
x =16.4 -0.14
x =16.26 (16.26/2 =0.7 =8.20 )