问题
解答题
计算下列各题，能简算的要简算．
3-
12÷[(
|
答案
①
×5753 56
=
×（56+1）53 56
=
×56+53 56
×153 56
=53+53 56
=53
；53 56
②
÷5 12
+3 4
÷5 12 1 4
=
×5 12
+4 3
×5 12 4 1
=
×（5 12
+4 3
）4 1
=
×55 12 1 3
=2
；2 9
③3-
÷8 9
×5 6 3 16
=3-
×8 9
×6 5 3 16
=3-1 5
=2
；4 5
④12÷[（
-7 9
）×2 3
]9 10
=12÷（
×7 9
-9 10
×2 3
）9 10
=12÷（
-7 10
）6 10
=12÷1 10
=120．