Đáp án: `+` Giải thích các bước giải:

`a) 15 : (x +2) = 3`

`x + 2 = 15 : 3`

`x + 2 = 5`

`x = 5 - 2`

`x= 3`

`b) 20 : (1+x)=2`

`1+x=20:2`

`1+x=10`

`x=10-1`

`x=9`

`c) 240 : (x-5) = 2^2 . 5^2 - 20`

`240 :(x-5)=4.25-20`

`240:(x-5)=100-20`

`240:(x-5)=80`

`x-5=240:80`

`x-5=3`

`x=3+5`

`x=8`

`d) 96 - 3(x+1)=42`

`3(x+1)=96-42`

`3(x+1)=54`

`x+1=54:3`

`x+1=18`

`x=18-1`

`x=17`

`e) 5(x+35)=515`

`x+35=515:5`

`x+35=103`

`x=103-35`

`x=68`

`f) 12x - 33 = 3^2 . 3^3`

`12x-33=3^5`

`12x - 33= 243`

`12x = 243 + 33`

`12x = 276`

`x = 276 :12`

`x= 23`

`g) 541 - (218+x)=73`

`218+x=541-73`

`218+x=468`

`x=468-218`

`x=250`

`h) 1230 : 3(x-20)=10`

`3(x-20)=1230:10`

`3(x-20)=123`

`x-20=123:3`

`x-20=41`

`x=41+20`

`x=61`

~𝓶𝔂𝓯𝓻𝓲𝓮𝓷𝓭𝓵𝔂~

Giải thích các bước giải:

Bài 3:

a) 15 : (x + 2) = 3

x + 2 = 15 : 3

x + 2 = 5

x = 5 - 2

x = 3

b) 20 : (1 + x) = 2

1 + x = 20 : 2

1 + x = 10

x = 10 - 1

x = 9

c) 240 : (x - 5) = 2^2 . 5^2 - 20

240 : (x - 5) = 4 . 25 - 20

240 : (x - 5) = 100 - 20

240 : (x - 5) = 80

x - 5 = 240 : 80

x - 5 = 3

x = 5 + 3

x = 8

d) 96 - 3(x + 1) = 42

3(x + 1) = 96 - 42

3(x + 1) = 54

x + 1 = 54/3

x + 1 = 18

x = 18 - 1

x = 17

e) 5(x + 35) = 51

5x + 35 = 515/5

x + 35 = 103

x = 103 - 35

x = 68

f) 12x - 33 = 3^2 . 3^3

12x - 33 = 3^5

12x - 33 = 243

12x = 243 + 33

12x = 276

x = 276 : 12

x = 23

g) 541 - (218 + x) = 73

218 + x = 541 - 73

218 + x = 468

x = 468 - 218

x =250

h) 1230 : 3(x - 20) = 10

3(x - 20) = 1230 : 10

3(x - 20) = 123

x - 20 = 123/3

x - 20 = 41

x = 41 + 20

x = 61

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