plssssssss làm giúp ạ

`4.`

`a) 7/2 - [3/2 + (x - 7/2)] = 9/11`

`7/2 - 3/2 - x + 7/2 = 9/11`

`(7/2 - 3/2 + 7/2) - x = 9/11`

`11/2 - x = 9/11`

`x = 11/2 - 9/11`

`x = 121/22 - 18/22`

`x = 103/22`

`b) 9/2 - [(x + 7/4) - 2/3] = 5/4`

`9/2 - x - 7/4 + 2/3 = 5/4`

`(9/2 - 7/4 + 2/3) - x = 5/4`

`(54/12 - 21/12 + 8/12) - x = 5/4`

`41/12 - x = 5/4`

`x = 41/12 - 5/4`

`x = 41/12 - 15/12`

`x = 26/12`

`x = 13/6`

`c) x - [17/2 - (5/3 - 3/7)] = 1/3`

`x - [17/2 - (35/21 - 9/21)] = 1/3`

`x - [17/2 - 26/21] = 1/3`

`x - [357/42 - 52/42] = 1/3`

`x - 305/42 = 1/3`

`x = 1/3 + 305/42`

`x = 319/42`

`5.`

`1) x/12 = 2/3 - 1/4`

`x/12 = 8/12 - 3/12`

`x/12 = 5/12`

`=> x = 5`

`2) x/5 = 5/6 - 1/30`

`x/5 = 25/30 - 1/30`

`x/5 = 24/30`

`x/5 = 4/5`

`=> x = 4`

`3) 1/x = 17/72 - 1/9`

`1/x = 17/72 - 8/72`

`1/x = 9/72`

`1/x = 1/8`

`=> x = 8`

`4) 3/x = 5/8 - 11/56`

`3/x = 35/56 - 11/56`

`3/x = 24/56`

`3/x = 3/7`

`=> x = 7`

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