(1)x-12%x=2.816,
(1-12%)x=2.816,
0.88x=2.816,
0.88x÷0.88=2.816÷0.88,
x=3.2;
(2)
×4 5
-1 4
x=1 2
,1 20
-1 5
x=1 2
,1 20
-1 5
x+1 2
x=1 2
+1 20
x,1 2
+1 20
x=1 2
,1 5
+1 20
x-1 2
=1 20
-1 5
,1 20
x=1 2
,3 20
x×2=1 2
×2,3 20
x=
.3 10