1.8x+x=42
6+0.3x=69
+=
÷2=
1.25×80%=
1÷=
:=
5÷20%=
-=
1.8×=
① ②
①0.53×2.5+
②25×0.032×12.5
③ [()×]
④6.83+17.9﹣0.83+32.1