115 - ( -85) + 53 - (2² - 3³) + `(-2017)^0`
= 115 + 85 + 53 - 4 + 9 + 1
=200 + 53 - 4 + 9 + 1
= 253 - 4 +( 9 + 1)
= 249 + 10
= 259
b) `(` `2/3` - `5/6` + `3/4` `)` : `-35/24`
= ( `-1/6` + `3/4` ) : `-35/24`
=`7/12` : `-35/24`
= `-2/5`
c) 75% - ( 1 - `3/4`) . `2/3` - `8/7` . ( `1/2`)²
=`3/4` - `1/4` . `2/3` - `8/7` . `1/4`
= `3/4` - `1/6` - `2/7`
= `7/12` - `2/7`
= `25/84`
d) [(2`1/2` - 0,25):`3/8` - `5/3`]- ( `2/3`)²
= [(`5/2` - `1/4`):`3/8` - `5/3`]- `4/9`
= [`9/4` :`3/8` - `5/3`] - `4/9`
=[ 6 - `5/3`] - `4/9`
= `13/3` - `4/9`
= `35/9`
bài 2)
a) `7/8` + `2,5` `x` = `5/6`
2,5 `x` = `5/6` - `7/8`
`5/2` `x` = `-1/24`
`x` = `-1/24` : `5/2`
`x` = `-1/60`
b) 2 ( `x` - `1/3`) = `5/9`
( `x` - `1/3` ) = `5/9` : 2
`x` - `1/3` = `5/18`
`x` = `5/18` + `1/3`
`x` = `11/18`
c) 4 - ( `1/2` `x` + `3/4`) = -1,5
4 - ( `1/2` `x` + `3/4`) = `-3/2`
( `1/2` `x` + `3/4`) = 4 - `-3/2`
`1/2` `x` + `3/4` = `11/2`
`1/2` `x` = `11/2` - `3/4`
`1/2` `x` = `19/4`
`x` = `19/4` : `1/2`
`x` = `19/2`
