①
②
③
④
⑴12×=
×7.2=
12÷=
×=
⑵0÷=
0.42÷=
÷=
+=
⑶÷2=
1.8×=
÷0.5=
-=
⑷÷+=
1--=
×9 ÷=
×÷×=
①2:0.75
②:
③:2
× ÷ ÷6 a+a×(a>0)