27+21=48

23+24=47

123+321=444

k cho mk nha

27+21=48

23+24=47

123+321=444

mình nhanh nhất 

a, 3.(37 - \(x\)) - 56 = 1

   3.(37 - \(x\)) = 1 + 56

   3.(37 - \(x\)) = 57

       37 - \(x\) = 57 : 3

       37 - \(x\) = 19

               \(x\) = 37 - 19

                \(x\) = 18

b, 95 - (2\(x\) - 1).4 = 14

           (2\(x\) - 1).4 = 95 - 14

           (2\(x\) - 1).4 = 81

             2\(x\) - 1 = 81 : 4

             2\(x\)      = \(\dfrac{81}{4}\) - 1

             2\(x\)     = \(\dfrac{85}{4}\)

              \(x\)    = \(\dfrac{85}{4}\) : 2

               \(x\)    = \(\dfrac{85}{8}\)

\(a,\Rightarrow x+35=103\\ \Rightarrow x=68\\ b,\Rightarrow x+7=42\\ \Rightarrow x=35\\ c,\Rightarrow x-15=9\\ \Rightarrow x=24\\ d,\Rightarrow x+23=31\\ \Rightarrow x=8\\ e,\Rightarrow18-x=6\\ \Rightarrow x=12\\ f,\Rightarrow x+14=34\\ \Rightarrow x=20\\ g,\Rightarrow2x+1=21\\ \Rightarrow x=11\\ h,\Rightarrow3\left(x+1\right)=99\\ \Rightarrow x+1=33\Rightarrow x=32\\ i,5\left(x-3\right)=25\\ \Rightarrow x-3=5\\ \Rightarrow x=8\\ j,\Rightarrow8\left(2x+7\right)=88\\ \Rightarrow2x+7=11\Rightarrow x=2\\ k,\Rightarrow5\left(x+4\right)=85\\ \Rightarrow x+4=17\\ \Rightarrow x=13\)

Cau 1)

21+(x+23)=50

X+23=50-21

X=29-23

X=6

Cau 2)

125+(x-100)=150

X-100=150-125

X=25+100

X=125

a. 123.1001

= 123.(1000+1)

= 123.1000+123.1

= 123000+123

= 123123

b. 98.321

= (100-2).321

= 100.321-2.321

= 32100-642

= 31458

Bài 1:

a, 35 + 28 - 42 - 35 - 28

= (35 - 35) + (28 - 28) - 42

= -42

b, 55 +56 +57 +58 +59 -28 -26 -25 -29 -27

=(55-25)+(56-26)+(57-27)+(58-28)+(59-29)

= 30 + 30 + 30 + 30 + 30

= 150

Bài 2:

a, -1983 - (325 - 1983)

= -1983 - 325 + 1983

= -325

b, -549 + (321 + 549)

= -549 + 321 + 549

= 321

c, 54 - (-65 + 98 - 15)

= 54 + 65 - 98 + 15

= 36

d, (67 + 23) - (56 - 32 + 46)

= 67 + 23 - 56 + 32 - 46

= 20

e, 24 - [ 15 - (42 - 18) ]

= 24 - [ 15 - 42 + 18 ]

= 24 - (-9)

= 33

f, (63 - 21 + 84) - (49 - 36 + 87)

= 63 - 21 + 84 - 49 + 36 - 87

= 26

g, 284 - [ (214 - 168) - (865 - 987) ]

= 284 - [ 214 - 168 - 865 + 987 ]

= 284 - 168

= 116

h, 654 + [ (545 - 726) - (321 - 465) ]

= 654 + [ 545 - 726 - 321 + 465 ]

= 654 + (-37)

= 617

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