`text(Bài 1 : Tính)`
`text(a))`
`4545/5757 - 151515/191919`
`= 45/57 - 15/19`
`= 45/57 - 45/57`
`= 0`
`text(b))`
`17/2 - (3/5 + 9/2)`
`= 85/10 - 51/10`
`= 34/10`
`= 17/5`
`text(c))`
`1/2 - (3/4 + -5/6) - 5/6`
`= 1/2 - 3/4 + 5/6 - 5/6`
`= -1/4 + 0`
`= -1/4`
`text(d))`
`1/3 - (3/5 + -5/2) + 3/5`
`= 1/3 - 3/5 + 5/2 + 3/5`
`= 1/3 + 5/2 - 3/5 + 3/5`
`= 17/6 - 0`
`= 17/6`
`text(Tìm x :)`
`text(a))`
`x - 1/5 = 3/7`
`⇒ x = 3/7 + 1/5`
`⇒ x = 22/35`
`text(b))`
`x + 3/4 = 1/2`
`⇒ x = 1/2 - 3/4`
`⇒ x = -1/4`
`text(c))`
`11/12 - (2/5 - x) = 2/3`
`⇒ 2/5 - x = 11/12 - 2/3`
`⇒ x = 2/5 - 9/36`
`⇒ x = 3/20`
`text(d))`
`-x + 2/3 = 3/5 - (-1/6)`
`⇒ -x + 2/3 = 23/30`
`⇒ -x = 23/30 - 2/3`
`⇒ -x = 1/10`
`⇒ x = -1/10`