`x/7 = 22/77`

`=>77x= 22.7`

`=>77x= 154`

`=>x=154:77`

`=>x=2`

\(\dfrac{2}{7}\)= \(\dfrac{22}{77}\)

2 nha

Bài 1:

a. 

$-12-(-46)=-12+46=46-12=34$

b.

$-(-8)-54=8-54=-(54-8)=-46$

c.

$-15-(-72)=-15+72=72-15=57$

Bài 2:

a. $(156-812)-(156-12)=156-812-156+12$

$=(156-156)-(812-12)=0-800=-800$

b.

$-(-72+83)-(72+17)=72-83-72-17=(72-72)-(83+17)$

$=0-100=-100$

c.

$-(-23-78)+(77-178)=23+78+77-178$

$=(23+77)-(178-78)=100-100=0$

d.

$(-213-156)-(-213+44)=-213-156+213-44=(-213+213)-(156+44)$

$=0-200=-200$

Trả lời :
13 + 9 = 22     

2333 - 213 = 2120

1238 : 2 = 619       

 56 x 77 = 4312

13 + 9 = 22

2333 - 213 = 2120

1238 : 2 = 619

56 x 77 = 4312

Ta có :

 \(77\times77=77\times\left(69+1+7\right)\)\(=77\times7+77+77\times69\)

=77(5x7+65)-21x57-21x43

=77x100-(21x57+21x43)

=7700-21(57+43)

=7700-21.100

=7700-2100

=5600

a, -(x+84) + 213=-16

-(x+84)+231=-16

-(x+84)=-16-231

-(x-84)=-247

=>x+84=247

x=247-84

x=163

b, -12 (x-15)+ 7(3-x) = 15

-12x+180+21-7x=15

(-12x-7x)+(180+21)=15

-19x+201=15

-19x=15-201

-19x=-186

x=-186:-19

x=186/19

a, x = 163

b, x = 186/19

k cho minh nha