2/15-2/65-4/39=4/39-4/39=0

32/13-(7/23+8/23)=32/13-15/23=541/299

(1/3+12/67+13/41) - (79/67 - 28/41)=6836/8241-1363/2747=1/3

38/145 - (8/45-17/51-3/11)=38/145-(-212/495)=1982/2871

a) 2/9 - (1/20 + 2/9)

= 2/9 - 1/20 - 2/9

= (2/9 - 2/9) - 1/20

= 0 - 1/20

= -1/20

b) -3/14 + 2/13 + (-25/14) + (-15/13)

= (-3/14 - 25/14) + (2/13 - 15/13)

= -2 - 1

= -3

c) -3/11 + 11/8 - 3/8 + (-8/11)

= (-3/11 - 8/11) + (11/8 - 3/8)

= -1 + 1

= 0

d) 3/8 + (-1/4) - (7/12 - 1/6)

= 1/8 - 5/12

= -7/24

e) (1/3 + 12/67 + 13/41) - (79/67 - 28/41)

= 1/3 + 12/67 + 13/41 - 79/67 + 28/41

= 1/3 + (12/67 - 79/67) + (13/41 + 28/41)

= 1/3 - 1 + 1

= 1/3

a)\(\dfrac{-10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

=\(\dfrac{10}{11}.\dfrac{-8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)

=\(\dfrac{10}{11}(\dfrac{-8}{9}+\dfrac{7}{18})\)

=\(\dfrac{10}{11}.\dfrac{-1}{2}\)

=\(\dfrac{-5}{11}\)

b; 

B = \(\dfrac{3}{14}\) : \(\dfrac{1}{28}\) - \(\dfrac{13}{21}\): \(\dfrac{1}{28}\) + \(\dfrac{29}{42}\) : \(\dfrac{1}{28}\) - 8

B = (\(\dfrac{3}{14}\) - \(\dfrac{13}{21}\) + \(\dfrac{29}{42}\)) - 8

B = (\(\dfrac{9}{42}\) - \(\dfrac{26}{42}\) + \(\dfrac{29}{42}\)) - 8

B = (\(\dfrac{-17}{42}\) + \(\dfrac{29}{42}\)) - 8

B = \(\dfrac{2}{7}\) - 8

B = \(\dfrac{2}{7}-\dfrac{56}{7}\)

B = - \(\dfrac{54}{7}\)

c; C = -1\(\dfrac{5}{7}\).15 + \(\dfrac{2}{7}\)(-15) + (-105).(\(\dfrac{2}{3}\) - \(\dfrac{4}{5}\) + \(\dfrac{1}{7}\))

C = - 15.(- 1 - \(\dfrac{5}{7}\) + \(\dfrac{2}{7}\) + \(\dfrac{14}{3}\) - \(\dfrac{28}{5}\) + \(1\))

C = -15.[(1 - 1) - (\(\dfrac{5}{7}\) - \(\dfrac{2}{7}\)) + \(\dfrac{14}{3}\) - \(\dfrac{28}{5}\)]

C = -15.[0 - \(\dfrac{3}{7}\) + \(\dfrac{14}{3}\) - \(\dfrac{28}{5}\)]

C = -15 . [- \(\dfrac{45}{105}\) + \(\dfrac{490}{105}\)  - \(\dfrac{588}{105}\)]

C = -15. [ \(\dfrac{445}{105}\) - \(\dfrac{588}{105}\)]

C = - 15.(- \(\dfrac{143}{105}\))

C = \(\dfrac{143}{7}\)

a,15/8

b, 73/56

c,1/6

d,4

đúng nhé bạn

a,15/8

b, 73/56

c,1/6

d,4

3/4+1/2 +5/8 = 5/4 + 5/8 =15/8

b, 1/47/56 - 15/28= 73/ 56

c, 11/30 - 1/5 = 1/6

d tương tự nhé

a. - 7 - 9 = - (7 + 9) = - 16

b. - 15 - 8 = - (15 + 8) = - 23

c. - 28 - 32 = - (28 + 32) = - 60

d. - 43 - 32 = - (43 + 32) = - 75

e. - 5 - 9 - 11

= - (5 + 9 + 11)

= - (14 + 11)

= - 25

f. - 6 - 8 - 13

= - (6 + 8 + 13)

= - (14 + 13)

= - 27

g. - 3 - 7 - 25

= - (3 + 7 + 25)

= - (10 + 25)

= - 35

h. - 7 - 4 - 15

= - (7 + 4 + 15)

= - (11 + 15)

= - 26

a) 15 x 21 - 16 : 4 + 7 

=    315    -      4    + 7

=           311   +     7

=             318

b) 123 - 11 x 6 + 150 : 30

=  123 -    66    +      5

=      57      +     5

=        62

Mình chỉ làm đến đó thôi chứ mấy câu còn lại khó hiểu quá!Ở lớp 5 mình chưa học bao giờ.

a)

=315-4+7=318

b)

=123-66+5=62

c)

=2017+5x[300-700:7]

=2017+5x[300-100]

=2017+5x200

=2017+1000

=3017

d)

=1560:[5x79-370+5x21]

=1560:[395-370+105]

=1560:130

=12

e)

=50-[12:2+34]

=50-40

=10

g)

=10-[16x5+88]:28

=10-168:28

=10-6

=4

a) 15x21 -16:4 +7

= 315-4 +7

=311+7

=318

b) 123 -11x6+150:30

=123-66+5

=57+5

=62

c)2017+5x[300-(715-15):7

=2017+5x[300-(700:7)

=2017+5x[300-100]

=2017+5x200

=2017+1000

=3017

5/7:15/28=4/3

9/11:21/22=6/7

7/9:5/6=14/15

8/15:16/25=5/6

k cho mình nhé

dung roi

a=4/3

b=6/7

c=14/15

d=5/6

Đăng lần lượt nhiều nhất 3 câu hỏi thôi, chứ đăng nhiều vậy, thấy nhát làm lắm.