25: \(\left(-25\right)+8-3\)

\(=\left(-25\right)+\left(8-3\right)\)

=-25+5

=-20

26: \(\left(-28\right)+2+6\)

\(=\left(-28\right)+\left(2+6\right)\)

=-28+8

=-20

27: \(\left(-1\right)+9+12\)

\(=\left(-1+12\right)+9\)

=11+9

=20

28: \(33+8-40\)

\(=\left(33+8\right)-40\)

=41-40

=1

29: \(\left(-80\right)+20+60\)

\(=\left(-80\right)+\left(20+60\right)\)

=-80+80

=0

30: \(\left(-12\right)+3+9\)

\(=\left(-12\right)+\left(3+9\right)\)

=-12+12

=0

25) (-25) + 8 - 3

= (-25 - 3) + 8

= -28 + 8

= -20

26) (-28) + 2 + 6

= -28 + 8

= -20

27) (-1) + 9 + 12

= -1 + (9 + 12)

= -1 + 21

= 20

28) 33 + 8 - 40

= (33 + 8) - 40

= 41 - 40

= 1

29) (-80) + 20 + 60

= -80 + (20 + 60)

= -80 + 80

= 0

30) (-12) + 3 + 9

= -12 + (3 + 9)

= -12 + 12

= 0

1: \(\left(-5\right)+8-7=8+\left(-5-7\right)\)

=-12+8

=-4

2: \(\left(-8\right)+2+8=\left(-8+8\right)+2=0+2=2\)

3: \(\left(-1\right)+3+1\)

\(=\left(-1+1\right)+3\)

=0+3

=3

4: \(\left(-6\right)+8-14\)

\(=\left(-6-14\right)+8\)

=-20+8

=-12

5: \(\left(-4\right)+3-7\)

\(=\left(-4-7\right)+3\)

=-11+3

=-8

6: \(\left(-4\right)+5-2\)

\(=\left(-4-2\right)+5\)

=-6+5

=-1

\(34\times76+66\times110+34\times34\)

\(=34\times\left(76+34\right)+66\times110\)

\(=34\times110+66\times110=110\times\left(34+66\right)=110\times100=110000\)

34 x 76 + 66 x 110 + 34 x 34

= 34 x ( 76 + 34 ) + 66 x 110

= 34 x 110 + 66 x 110

= 110 x ( 34 + 66 )

= 110 x 100

= 11 000

=))

34 x 76 + 66 x 110 + 34 x 34

= 34 x ( 76 + 34 ) + 66 x 110

= 34 x 110 + 66 x 110

= 110 x ( 34 + 66 )

= 110 x 100 

= 110000

Study well 

Bạn k k lên điểm đâu lên mk k cần đâu ạ 

b: I=-15+13=-2

(-12) + (-18)

= -30

------------------

(-90) + 27 + (-10) + 73

= [(-90) + (-10) + (27 + 73)

= -100 + 100

= 0

---------------------------------

25 . (-5) . (-4)

= 25 . (-4) . (-5)

= -100 . (-5)

= 100 . 5

= 500

----------------------------------------

(-15) . 40 : 6

= [(-15) . 40] : 6 

= (-600) : 6

= -100

-----------------------------------

(-27) . 58 + (-27) . 42

= (-27) . (58 + 42)

= (-27) . 100

= -2700

\(\frac{-1}{3}:\frac{-5}{6}=\frac{-1}{3}\times\frac{-6}{5}=\frac{2}{5}\)

@muối

(-1/3) : (-5/6) = 2/5

\(\frac{-1}{3}:\frac{-5}{6}\)

\(=\frac{-1}{3}.\frac{6}{-5}\)

\(=\frac{-6}{-15}\)

\(=\frac{-2}{-5}\)

\(=\frac{2}{5}\)

Câu 1:

A={1;3;5;7;9}

Câu 2: 

A. 24 x 82 + 24 x 18 - 100 

= 24 x (82 + 18) - 100

= 24 x 100 - 100

= 2400 - 100 = 2300

B.12 + 3 [ 39 - (5 - 2 )² ]

= 12 + 3. [39 - 3² ]

= 12 + 3 . [39-9]

= 12 + 3.30

= 12 + 90 = 102

=(-968+68)+(-35-65)

=-900+(-100)

=-1000

\(-968-35+68-65\)

\(=\left(968-68\right)+\left(-35-65\right)\)

\(=900+\left(-100\right)\)

\(=-1000\)

Chúc bạn học tốt~~~

Mình không chắc nữa nhưng bạn cứ làm thử đi nha !!!!

Câu 9

a) 2/15 + (-3/5)

= 2/15 - 3/5

= 2/15 - 9/15

= -7/15

b) -5/7 + 3/7 . (-2/9)

= -5/7 - 2/21

= -15/21 - 2/21

= -17/21

c) 5/16 - (7/15 - 3/16) + 17/30

= 5/16 - 7/15 + 3/16 + 17/30

= (5/16 + 3/16) + (17/30 - 14/30)

= 1/2 + 1/10

= 5/10 + 1/10

= 6/10

= 3/5

\(a,\dfrac{2}{15}+\left(-\dfrac{3}{5}\right)\\ =\dfrac{2}{15}-\dfrac{3}{5}\\ =\dfrac{2}{15}-\dfrac{9}{15}\\ =-\dfrac{7}{15}\\ b,-\dfrac{5}{7}+\dfrac{3}{7}\times\left(-\dfrac{2}{9}\right)\\ =-\dfrac{5}{7}-\dfrac{2}{21}\\ =-\dfrac{15}{21}-\dfrac{2}{21}\\ =-\dfrac{17}{21}\\ c,\dfrac{5}{16}-\left(\dfrac{7}{15}-\dfrac{3}{16}\right)+\dfrac{17}{30}\\ =\dfrac{5}{16}-\dfrac{7}{15}+\dfrac{3}{16}+\dfrac{17}{30}\\ =\left(\dfrac{5}{16}+\dfrac{3}{16}\right)-\left(\dfrac{17}{15}+\dfrac{17}{30}\right)\\ =\dfrac{1}{2}-\dfrac{17}{10}\\ =\dfrac{5}{10}-\dfrac{17}{10}\\ =-\dfrac{6}{5}.\)