a) (-21) + 24 + (-27) + 31

= 3 + (-27 + 31)

= 3 + 4

= 7

b) (62 - 81) - (12 - 59 + 9)

= -19 - (-47 + 9)

= -19 + 38

= -19

Bài 2:

a. $=62-81-12+59-9=(62-12)+(59-9)-81$

$=50+50-81=100-81=19$

b. $=39+13-26-62-39=(39-39)+13-(26+62)$

$=0+13-88=-(88-13)=-75$

c. $=(32-42)+(36-34)+(40-38)=10+2+2=14$
d. $=92-55+8-45=(92+8)-(55+45)=100-100=0$

Bài 1:

a. $=(387-87)-224=300-224=76$

b. $=-(75+35)+379=-110+379=379-110=269$

c. $=(11+15)-(13+17)=25-30=-5$

d. $=(31-21)-(27-24)=10-3=7$

`#040911`

`a)`

`27 \times 38 + 62 \times 27 - 27 \times 90`

`= 27 \times (38 + 62 - 90)`

`= 27 \times (100 - 90)`

`= 27 \times 10`

`= 270`

\(27\times38+62\times27-27\times90\)

\(=27\times\left(38+62-90\right)\)

\(=27\times\left(100-90\right)\)

\(=27\times10\)

\(=270\)

\(x=27.38+62.27-27.90\)

\(x=27.\left(38+62-90\right)\)

\(x=27.10\)

\(=270\)

x = 27*(38+62-90)

x = 27*10

x = 270

x = 27 x 38  + 62 x 27 - 27 x 90 .

x = 27 . ( 38 + 62 - 90 )

x = 27 . 10

x = 270 

giúp mik với

https://hoc24.vn/cau-hoi/a-5x-2x-62-50b-5x-x-150-2-3c-6x-x-511-59-31d-5x-3x-36-334-124x-2x-68-219-216.2785429565572

a: \(\Leftrightarrow7x=35\)

hay x=5

b: \(\Leftrightarrow6x=78\)

hay x=13

\(\left(62-81\right)-\left(12-59+9\right)\)

\(=\left(-19\right)-\left(-38\right)\)

\(=19\)

\(\text{( 62 - 81) - (12 - 59 + 9 ) }=\left(-19\right)-\left(-38\right)=\left(-57\right)\)

27 : x =  62 - 59

27 : x =  3

x = 29 : 3

x = 9

X x 3 = 46 - 16

X x 3 = 30

X = 30 : 3

X = 10

\(a,\Leftrightarrow27:x=3\)

\(\Leftrightarrow x=27:3\)

\(\Leftrightarrow x=9\)

\(b,\Leftrightarrow x\times3=30\)

\(\Leftrightarrow x=10\)

27:x= 62-59

=>27:x=3

=>x=29:3

x=9

x*3+16=46

=>x*3 = 46 - 16

=>X*3 = 30

=>x = 30 : 3

=> x =10

\(=62-81-12+59-9=19\)

\(\left(62-81\right)-\left(12-59+9\right)=-19-\left(-38\right)=-19+38=19\)

\(\left(62-81\right)-\left(12-59+9\right)=-19-\left(-47+9\right)=-19-\left(-38\right)=-19+38=19\)