(21 + 32) - (-12 + 32)

= 21 + 32 + 12 - 32

= (32 - 32) + (21 + 12)

= 0 + 33

= 33

- ( 21 + 32 ) - ( - 12 + 32 )

= ( - 21 ) + 32 - ( - 12 ) - 32

= ( - 21 ) + 32 + 12 - 32

= 11 + 12 - 32

= 23 - 32

= - 9.

-(21+32)-(-12+32)

= - 21 - 32 + 12 - 32

= ( - 21 + 12 ) + ( - 32 - 32 )

= - 9 - 62

= - 71

!!! k chắc

-(21+32)-(-12+32)

=-21-32-(-12)-32

=-21+(-32)+12+(-32)

=-21+12+(-32)+(-32)

=(-9)+(-64)=(-73)

Chúc bn học tốt

(− 21 − 32) − (−12 + 32) 

= −21 + 32 + 12 − 32

= −21 + 12 + 32 − 32

= −9 + 0

= −9 

nhớ k cho mình nha'

học tốt

a. = 12 - 25 + 36 - 12 + 36 - 57

= (12 - 12) + (36 + 36) - (25 + 57)

= 0 + 72 - 82

= -10

b. = -23 - 5 + 6 - 17 + 23 - 5 - 83 - 6

= (-23 + 23) + (-5 - 5) + (6 - 6) - (17 + 83)

= 0 + (-10) + 0 - 100

= -110

c.?

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ko bik

3,14 × 94 + 3,14 + 6,28 × 2 + 3,14

= 3,14x94+ 3,14x1+ 3,14x2x2+3,14x1

= 3,14(94+1+4+1)

=3,14x 100 

=314

(2,8x - 32) :2/3 = 90

2,8x-32= 90 * 2/3

2,8x-32 = 60

2,8x = 60 +32

2,8x =92

x= 92: 2,8

x=230/7

Đúng 100%, thử lại rồi

\(\left(2,8x-32\right):\frac{2}{3}=90\)

\(2,8x-32=90\cdot\frac{2}{3}=60\)

\(2,8x=60+32=92\)

\(x=\frac{92}{2,8}\approx32,9\)

(2,8.x-32):2/3=90

2,8.x-32=90.2/3

2,8.x-32=60

2,8.x=28

x=28:2,8

x=10

a-b+a+c nha bn

c nha bạn.

c.lấy chu vi chia cho 3,14 rồi chia 2 

florentino

\(7,1+\left(-5,25\right)-\left(-2,25+7,1\right)\)

\(=7,1-5,25+2,25-7,1\)

\(=\left(7,1-7,1\right)-\left(5,25-2,25\right)\)

\(=0+3\)

\(=3\)

Ủng hộ mk nha ^_-