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Trình bày lời giải:

Bài `1.`
`a)`
`73+169+17+31`
`=(73+17)+(169+31)`
`=90+200`
`=290`
`b)`
`28.56-28.46+72.55-72.45`
`=28.(56-46)+72.(55-45)`
`=28.10+72.10`
`=(28+72).10`
`=100.10`
`=1000`
`c)`
`181+87:29-7.12+2^3 . 5^2`
`=181+3-84+8.25`
`=181-81+200`
`=100+200`
`=300`
`d)`
`200-[69-(9-2)^2].3^2`
`=200-[69-7^2].9`
`=200-[69-49].9`
`=200-20.9`
`=200-180`
`=20`