的倒数是
的倒数是.
8:12
0.25:0.45
: .
+ =
2﹣ =
6× =
÷ =
﹣ =
× =
x+ x=
﹣x=
×x=
x÷ = .
﹣ + +
÷ + ÷ .
+( ﹣ )÷
+( + )×
( ﹣ )÷ + .