x = 8

ai tk mk 

mk tk lại

mk hứa

yên tâm

x + 45 = 57

x         = 57 - 45

x         = 12

Vậy x = 12

Chúc pn hok tốt !

162576

a) - ( 231 + 16 - 75 ) + ( 25 - 9 )

= - 231 - 16 + 75 + 25 - 9

= - 247 + 100 - 9

= -147 - 9

= -156

b) - ( - 231 + 17 ) - ( 54 + 23 )

= 231 +  17 - 54 - 23

= 248 - 31

= 217

c) - [ ( - 25 ) - 7 + ( 8 - 16 ) ] - [ ( - 21 + 3 ) - 7 ]

= - [-32 + (-8) ] - [ -18 - 7]

= - (-40) - (-25)

= 40 + 25

= 65

d) - ( - a - b - c ) + ( - c - b + a )

= a + b + c - c - b + a

= a+ b + 0 - b + a

= a + a + b - b 

= a + a + 0

= 2a

e) ( - 26 ) - [ - ( 18 - 6 + 7 ) + ( 8 - 9 ) ]

= -26 - [ -18 + 6 - 7 + 8 - 9]

= -26 - (-20)

= -26 + 20

= -6

469134 nhe

tăng thêm 5

 x²⁰¹⁵ - ( - 42 - 2x ) = 6 + x²⁰¹⁵

x²⁰¹⁵+42+2x=6+x²⁰¹⁵

^{......................................................................}

^x=18

x=500

200+400+500+600=1700

12345 + 456789 = 469134

k mình nha