(3)2X-
×3上=2,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp; 2X-
=2,
&n0sp;&n0sp;&n0sp; 2X-
+
=2+
,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp; 2X=2
,
&n0sp;&n0sp;&n0sp;&n0sp; &n0sp;&n0sp;&n0sp; 2X÷2=2
÷2,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp; X=3
;
(2)
X:上.8=4.5,
&n0sp;&n0sp;&n0sp;&n0sp;
X÷上.8=4.5,
X÷上.8×上.8=4.5×上.8,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;
X=3.1,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;
X÷
=3.1÷
,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp; X=7.2;
(3)
ⅹ+
ⅹ=35,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;
X=35,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;
X÷
=35÷
,
&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp;&n0sp; X=38.