①
②
③1﹣
④
①24和36
②33和66
③51和68
x+= x-=
① ② ③
④ ⑤ ⑥
0.68+19.6= = 0.56÷0.4= 0.125×8=
12= 0.22×200= 100﹣0.86= =
①÷×
②×3.2+6.8÷
③105×(+)
④﹣+﹣
⑤6.4÷[(3﹣1.4)×]