3. 315-(79+15) =315-15-79 =300-79 =221 45x0.99 =45x(1-0.01) =45x1-45x0.01 =45-0.45 =44.55 25x25x16 =(25x4)x(25x4) =100x100 =10000 720÷5÷6 =720÷(5x6) =720÷30 =24 540÷45 =540÷9÷5 =60÷5 =12
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4. 45x3.2÷48=3(小时) 答:3小时可以到达。 5. 3600÷(500+400) =3600÷900 =4(天) 答:两队同时安装,4天可以完成任务。 6. 250×2×7=3500(吨) 3500吨<4000吨 答:储备4000吨煤够。 |