Giải thích các bước giải:
`a)`
`(4/5-1/5xx3/5-1/3)`
`=(4/5-3/25-1/3)`
`=(20/25-3/25-1/3)`
`=(17/25-1/3)`
`=51/75-25/75`
`=26/75`
`b)`
`43,57xx2,6xx(630-315xx2)`
`=43,57xx2,6xx(630-630)`
`=43,57xx2,6xx0`
`=0`
`c)`
`654,72+306,5-437,05`
`=654,72+(306,5-437,05)`
`=654,72-130,55`
`=524,17`