①
②
③
④
⑤(3x+2)+2[(x-1)-(2x+1)]=6
⑥
①1.5x-2.8=4.7
③12: =
x÷(1﹣ ﹣25%)=2 .
1 :4=x:2.5; 4.9+50%x=6.3; 6.9﹣ x= .