故选:A.
四、算一算.
22.
直接写出得数.0.57+0.43=4.13﹣1.3=2.5×28=
7.2÷0.6=0.52=3﹣1=
(+
)=15÷
×
=
×8+8×
=
【解答】解:
0.57+0.43=1,4.13﹣1.3=2.83,2.5×28=70,
7.2÷0.6=12,0.52=0.25,3﹣1=1
,
+
=
,15÷
×
=15,
×8+8×
=12.
23.求未知数x.
2x﹣=0.5
x+x=
x÷
=35
0.36:x=:
.
【解答】解:(1)2x﹣=0.5,
2x﹣+
=0.5+
,
2x÷2=1÷2,
x=0.5;
(2)x+x=
,
x
=
,
x=;
(3)x÷
=35,
x÷
×
=35×
,
x=15,
x=18;
(4)0.36:x=:
,
x=0.36×
,
x
=0.16
,
x=1.6.
24.计算.
0.375×1+
×1.75
(﹣
)÷(4÷
)
[1﹣(+
)]÷
.
【解答】解:(1)0.375×1+
×1.75,
=×1
+
×1
,
=(+
)×1
,
=1;
(2)(﹣
)÷(4÷
),
=,