(1)9×6+x=76.8
54+x=76.8
54+x-54=76.8-54
x=22.8
(2)(1-45%)x=110
0.55x=110
0.55x÷0.55=110÷0.55
x=200
(3)
6
5 ÷x=
7
4 ×
2
3
6
5 ÷x×x=
7
6 ×x
7
6 x=
6
5
7
6 x×
6
7 =
6
5 ×
6
7
x=
36
35
(4)5.6x+12.88=42
5.6x+12.88-12.88=42-12.88
5.6x=29.12
5.6x÷5.6=29.12÷5.6
x=5.2