①1204+879+121
②74×60%+×25+0.6
③1.2÷×(0.6﹣)
④×[﹣(+)]
① ②
③ ④
①36×()
②1.3×37.5%+2.7×
③ [()]
④13÷()×
7.28﹣(1.28+0.25) ÷[×(0.5+)]
23× 3.7×+1.3÷