-1/16-1/5= -1/5 
11/36- - 7/24= 1/2
-5/9- - 5/12= -1/10 
chúc mày học dốt:)))

a) Ta có: BCNN(15,10) = 30 nên ta chọn mẫu số chung là 30

\(\frac{11}{15}+\frac{9}{10}=\frac{22}{30}+\frac{27}{30}=\frac{49}{30}\)

b) Ta có: BCNN(6,9,12) = 36 nên ta chọn mẫu số chung là 36

\(\frac{5}{6} + \frac{7}{9} + \frac{{11}}{{12}} = \frac{{30}}{{36}} + \frac{{28}}{{36}} + \frac{{33}}{{36}} = \frac{{91}}{{36}}\)

c) Ta có: BCNN(24,21) = 168 nên ta chọn mẫu số chung là 168

\(\frac{7}{{24}} - \frac{2}{{21}} = \frac{{49}}{{168}} - \frac{{16}}{{168}} = \frac{{33}}{{168}}=\frac{11}{56}\)

d) Ta có: BCNN(36,24) = 72 nên ta chọn mẫu số chung là 72

\(\frac{{11}}{{36}} - \frac{7}{{24}} = \frac{{22}}{{72}} - \frac{{21}}{{72}} = \frac{1}{{72}}\)

giúp mình với mọi người ơi, mình cần gấp :(

\(a,\left(36+79\right)+\left(145-79-36\right)\)

\(=36-36+79-79+145\)

\(=145\)

      6)(36+79)+(145-79-36)

         = 36+79+145-79-36

        = (36-36)+(79-79)+145

        =145

      7)3.10-[12-(-9-1)]

       =30-(12-9+1)

      =30-12+9-1

       =26

      8)45-5.(12+9)

   =45-60-45

=(45-45)-60

=0-60

=-60

      9)24.(16-5)-16.(24-5)

=24.16-14.5-16.24+16.5

=16.5-14.5

=5(16-14)

=5.2

=10

     10)-23.63+23.21-58.23

= 23(-63+21-58)

=23.-100

=-2300

      11)[(-851)+5924]+[(-5924)+851]

=-851+5924-5924+851

=(-851+851)+(5924-5924)

=0+0

=0

-5/9 - ( -5/12 ) =-5/9+5/12=-20/36+15/36=-5/36

-1/16 - 1/15=-15/240-16/240=-31/240

11/36 - ( -7/24 )=11/36+7/24=22/72+21/72 =43/72

\(-\frac{5}{9}-\left(-\frac{5}{12}\right)=-\frac{60}{108}-\left(-\frac{45}{108}\right)=-\frac{15}{108}=-\frac{5}{36}.\)

\(\frac{-1}{6}-\frac{1}{15}=\frac{-5}{30}-\frac{2}{30}=\frac{-7}{30}\)

\(\frac{11}{36}-\left(-\frac{7}{24}\right)=\frac{22}{72}-\left(-\frac{21}{72}\right)=\frac{43}{72}\)

Mk xin lỗi,mk ghi thiếu đề ạ!

\(\frac{-1}{16}-\frac{1}{15}=\frac{-15}{240}-\frac{16}{240}=\frac{-31}{240}.\)

5/7 va 28/7

19/24 va 168/24

9/11 va 55/11

16/36 va 21/36

k di

a: =-21/36-3/36=-24/36=-2/3

b: =43/12*1/2+5/24=43/24+5/24=2

c: =8/9+1/9=1

e: =1-1/4+1/4-1/7+...+1/97-1/100

=1-1/100=99/100

\(\left(a\right)\frac{3}{7}-\left(\frac{-2}{7}\right)=\frac{3}{7}+\frac{2}{7}=\frac{5}{7}\)

\(\left(b\right)\frac{-13}{11}+\frac{6}{22}-\frac{36}{33}=\frac{-39}{33}+\frac{9}{33}-\frac{36}{33}=\frac{-66}{33}=-2\)

\(a,\frac{3}{7}-\frac{-2}{7}=\frac{3-\left(-2\right)}{7}=\frac{3+2}{7}=\frac{5}{7}\)

\(b,-\frac{13}{11}+\frac{6}{22}-\frac{36}{33}=-\frac{13}{11}+\frac{3}{11}-\frac{12}{11}=\frac{-13+3-12}{11}=-\frac{22}{11}=-2\)

\(c,-\frac{6}{17}-\frac{5}{-12}+\frac{3}{81}=-\frac{6}{17}+\frac{5}{12}+\frac{1}{27}=\frac{-6.27.12+5.17.27+17.12}{17.12.27}=\frac{185}{1836}\)

\(\frac{2}{70}-\frac{9}{-24}+\frac{-5}{42}=\frac{1}{35}+\frac{3}{8}-\frac{5}{42}=\frac{1.24+105.3-5.20}{840}=\frac{239}{840}\)