(1)4x-3.2=10.4,
4x-3.2+3.2=10.4+3.2,
4x=13.6,
4x÷4=13.6÷4,
x=3.4;
(2)12:x=
3
5 :
1
4 ,
12:x=12:5,
12x=60,
12x÷12=60÷12,
x=5.