①1.5x-2.8=4.7
②
③12: =
①58+399=
②1122÷11=
③0.1÷=
④×54=
⑤0.24×5=
⑥1÷0.375=
⑦-=
⑧20÷10%=
⑨23+12=
⑩12×()=
⑪0.25×4÷0.25×4=
⑫+÷+=
①
③
④
⑤(3x+2)+2[(x-1)-(2x+1)]=6
⑥
x÷(1﹣ ﹣25%)=2 .
1 :4=x:2.5; 4.9+50%x=6.3; 6.9﹣ x= .
50%x﹣0.2x=15; x =12; 6:30=x:0.5.