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

Chọn C

`Answer:`

a. \(-\frac{17}{30}-\frac{11}{-15}+-\frac{7}{12}\)

\(=-\frac{17}{30}+\frac{11}{15}-\frac{7}{12}\)

\(=-\frac{17}{30}+\frac{22}{30}-\frac{7}{12}\)

\(=\frac{1}{6}-\frac{7}{12}\)

\(=-\frac{5}{12}\)

b. \(-\frac{5}{9}+\frac{5}{9}:\left(\frac{5}{3}-\frac{25}{12}\right)\)

\(=-\frac{5}{9}+\frac{5}{9}:\left(-\frac{5}{12}\right)\)

\(=\frac{5}{9}.\left(-1\right)+\frac{5}{9}.\left(-\frac{12}{5}\right)\)

\(=\frac{5}{9}.\left(-1-\frac{12}{5}\right)\)

\(=\frac{5}{9}.\frac{-17}{5}\)

\(=-\frac{17}{9}\)

c. \(-\frac{7}{25}.\frac{11}{13}+-\frac{7}{25}-\frac{2}{13}-\frac{18}{25}\)

\(=\frac{77}{325}-\left(\frac{7}{25}+\frac{18}{25}\right)-\frac{2}{13}\)

\(=\frac{77}{325}-1-\frac{2}{13}\)

\(=-\frac{452}{325}\)

a: =35/17-18/17-9/5+4/5

=1-1=0

b: =-7/19(3/17+8/11-1)

=7/19*18/187=126/3553

c: =26/15-11/15-17/3-6/13

=1-6/13-17/3

=7/13-17/3=-200/39

`a)3/5+(-4/9)`

`=3/5-4/9`

`=27/45-20/45`

`=7/45`

`b)3/5+2/5 . 15/8`

`=3/5 + 30/40`

`=3/5+3/4`

`=12/20+15/20`

`=27/20`

`c)7/2 . 8/13 + 8/13 . (-5/2)`

`=8/13 . (7/2 +(-5)/2)`

`=8/13 . 1`

`=8/13`

`d)-5/17 . (-9/23)+9/23 . (-22/17) + 11 9/23`

`=-5/17 . (-9/23) + 9/23 . (-1) . 22/17 + 11 + 9/23`

`=-5/17 . (-9/23) + (-9/23) . 22/17+11+9/23`

`= -9/23 ( -5/17 + 22/17)+11+9/23`

`= - 9/23 . 1+11+9/23`

`=-9/23+11+9/23`

`=(-9/23+9/23)+11`

`=0+11`

`=11`

a: =27/45-20/45=7/45

b: =3/5+30/40

=3/5+3/4

=12/20+15/20

=27/20

c: =8/13(7/2-5/2+1)=8/13*2=16/13

d: =9/23*5/17-9/23*22/17+11+9/23

=-9/23+11+9/23

=11

a; - \(\dfrac{10}{13}\) + \(\dfrac{5}{17}\) - \(\dfrac{3}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{11}{20}\)

= - (\(\dfrac{10}{13}\) + \(\dfrac{3}{13}\)) + (\(\dfrac{5}{17}\) + \(\dfrac{12}{17}\)) - \(\dfrac{11}{20}\)

= - 1 + 1  - \(\dfrac{11}{20}\)

=   0 - \(\dfrac{11}{20}\)

= - \(\dfrac{11}{20}\)

b; \(\dfrac{3}{4}\) + \(\dfrac{-5}{6}\) - \(\dfrac{11}{-12}\)

= \(\dfrac{9}{12}\) - \(\dfrac{10}{12}\) + \(\dfrac{11}{12}\)

= \(\dfrac{10}{12}\)

= \(\dfrac{5}{6}\)

c; [13.\(\dfrac{4}{9}\) + 2.\(\dfrac{1}{9}\)] - 3.\(\dfrac{4}{9}\)

= [\(\dfrac{52}{9}\) + \(\dfrac{2}{9}\)] - \(\dfrac{4}{3}\)

= \(\dfrac{54}{9}\) - \(\dfrac{4}{3}\)

= \(\dfrac{14}{3}\)

dài quá ko làm đâu

a ) 9 13 b ) 11 − 5 c ) − 4 11 . d ) − 2 − 13 .

a)  9 13

b)  11 - 5

c)  - 4 11

d)  - 2 - 13