Bài 1.
a) `1/3 + 2/4 - 5/6`
`= 4/12 + 6/12 - 10/12`
`= 10/12 - 10/12`
`= 0/12`
b) `15/2 - (75/100 + 3/8) : 3/4`
`= 15/2 - (600/800 + 300/800) : 3/4`
`= 15/2 - 900/800 : 3/4`
`= 15/2 - 9/8 : 3/4`
`= 15/2 - 9/8 . 4/3`
`= 15/2 - 3/2 . 1/1`
`= 15/2 - 3/2`
`= 12/2 = 6`
Bài 2.
a) `-18/x = 3/4`
`x = 18 . 4 : 3`
`x = 24`
Vậy x = 24
b) `-3/5 x + 2/3 = 11/3`
`-3/5 x = 11/3 - 2/3`
`-3/5 x = 9/3`
`x = 9/3 : -3/5`
`x = 9/3 . -5/3`
`x = -45/9`
`x = -5`
Vậy x = -5
