a: =-1+17/20=-3/20

b: =(28/60-33/60)*(-25/3)

=(-1/12)*(-25/3)=1/12*25/3=25/36

c: \(=\dfrac{1}{3}\cdot\dfrac{1}{3}=\dfrac{1}{9}\)

a. (7/15 + 8/15) + (22/12 + 2/12) 

= 1 + 24/12

= 1 + 2

=3

b.(9/7 + 5/7) + (16/20 + 4/20)

= 14/7 + 20/20

= 2 + 1

= 3

\(a,\dfrac{7}{15}+\dfrac{22}{12}+\dfrac{8}{15}+\dfrac{2}{12}\\ =\left(\dfrac{7}{15}+\dfrac{8}{15}\right)+\left(\dfrac{22}{12}+\dfrac{2}{12}\right)\\ =\dfrac{15}{15}+\dfrac{24}{12}\\ =1+2\\ =3\\ b,\dfrac{9}{7}+\dfrac{16}{20}+\dfrac{4}{20}+\dfrac{5}{7}\\ =\left(\dfrac{9}{7}+\dfrac{5}{7}\right)+\left(\dfrac{16}{20}+\dfrac{4}{20}\right)\\ =\dfrac{14}{7}+\dfrac{20}{20}\\ =2+1\\ =3\)

a, (7/15+8/15)+(22/12+2/12)

=1+2=3

\(a,\dfrac{1}{2}=\dfrac{2}{4}=\dfrac{4}{8}=\dfrac{3}{6}\\ b,\dfrac{1}{4}=\dfrac{2}{8}=\dfrac{3}{12}=\dfrac{5}{20}\\ c,\dfrac{2}{5}=\dfrac{8}{20}=\dfrac{10}{25}\)

=9/20 - 2/9

=41/180

41/180

   9/20 - 8/15 x 5/12

= 9/20 - 2/9

= 41/180

câu a : 

\(\dfrac{-8}{24}+\dfrac{-4}{12}=\dfrac{-1}{3}+\dfrac{-1}{3}=\dfrac{-2}{3}\)

câu b : 

\(\dfrac{-20}{35}+\dfrac{16}{24}=\dfrac{-4}{7}+\dfrac{2}{3}=\dfrac{2}{21}\)

câu c : 

\(\dfrac{-3}{9}+\dfrac{-6}{15}=\dfrac{-1}{3}+\dfrac{-2}{5}=\dfrac{-11}{15}\)

câu d : 

\(\dfrac{3}{13}-\dfrac{4}{10}=\dfrac{3}{13}-\dfrac{2}{5}=\dfrac{-11}{65}\)

câu e : 

\(\dfrac{5}{17}-\dfrac{9}{15}=\dfrac{5}{17}-\dfrac{3}{5}=\dfrac{-26}{85}\)

câu g : 

\(\dfrac{9}{18}-\dfrac{6}{15}+\dfrac{3}{-9}=\dfrac{9}{18}-\dfrac{6}{15}+\dfrac{-3}{9}\\ =\dfrac{1}{2}-\dfrac{2}{5}+\dfrac{-1}{3}=\dfrac{-7}{30}\)

câu h : 

\(\dfrac{5}{4}-\dfrac{1}{2}+\dfrac{-7}{8}=\dfrac{10}{8}-\dfrac{4}{8}+\dfrac{-7}{8}=\dfrac{-1}{8}\)

\(a)\frac{4}{9}+\frac{11}{8}-\frac{5}{6}\)

\(=\frac{32}{72}+\frac{99}{72}-\frac{60}{72}\)

\(=\frac{71}{72}\)

\(b)\frac{9}{20}-\frac{8}{15}.\frac{5}{12}\)

\(=\frac{9}{20}-\frac{2}{9}\)

\(=\frac{81}{180}-\frac{40}{180}=\frac{41}{180}\)

giúp mình nha

9/20-8/15.5/12=9/20-2/9=41/180

41/180

\(\frac{41}{180}\)