`e ) 5x - 210 : 7 = 90`
`5x - 30 = 90`
`5x = 90 + 30`
`5x = 120`
`x = 120 : 5`
`x = 24`
Vậy `x = 24`
`f ) 80 : 5 - 2x = 10`
`16 - 2x = 10`
`2x = 16 - 10`
`2x = 6`
`x = 6 : 2`
`x = 3`
Vậy `x = 3`
`e ) ( 7x - 13 ) . 2020 = 2020`
`7x - 13 = 2020 : 2020`
`7x - 13 = 1`
`7x = 1 + 13`
`7x = 14`
`x = 14 : 7`
`x = 2`
Vậy `x = 2`
`f ) 44 + 7 . ( x + 3 ) = 100`
`7. ( x + 3 ) = 100 - 44`
`7 . ( x + 3 ) = 56`
`x + 3 = 56 : 7`
`x + 3 = 8`
`x = 8 - 3`
`x = 5`
Vậy `x = 5`
`#dtkc`
