①1204+879+121
②74×60%+×25+0.6
③1.2÷×(0.6﹣)
④×[﹣(+)]
1÷0.05= 9.7+0.03= 1-1÷9= 12×( + )=
× = + = 0.6÷ = 2÷1%=
①x+x=42
②=
59×101
[2-( + )]÷
2.5÷ ×
12.5×4.8+87.5×4.8
18:15和0.6:0.5 : 和 :2 0.4:0.8和0.5:0.2 16:8和1.2:0.6