+=
1-=
++=
0.5+=
-=
2--=
12.4+8.6=
3.6÷0.9=
4a+1.2a=
4×0.25÷0.25×4=
2-=
12÷18=
1.45+6.7=
8×0.125=
23=
-=
+=
1-=
+=
+2=