Question

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Answer 1

\(a,\dfrac{5}{12}-\dfrac{3}{9}+\dfrac{1}{18}=\dfrac{15}{36}-\dfrac{12}{36}+\dfrac{2}{36}=\dfrac{3}{36}+\dfrac{2}{36}=\dfrac{5}{36}\\ b,\dfrac{-2}{5}-\dfrac{3}{5}.\dfrac{4}{9}=\dfrac{-2}{5}-\dfrac{12}{45}=\dfrac{-18}{45}-\dfrac{12}{45}=\dfrac{-30}{45}=\dfrac{-2}{3}\)

\(c,\dfrac{2}{9}-\dfrac{-5}{12}+\dfrac{-3}{4}=\dfrac{2}{9}+\dfrac{5}{12}+\dfrac{-3}{4}=\dfrac{8}{36}+\dfrac{15}{36}+\dfrac{-27}{36}=\dfrac{23}{36}+\dfrac{-27}{36}=\dfrac{-4}{36}=\dfrac{-1}{9}\)

\(d,\dfrac{7}{12}-\dfrac{27}{7}:\dfrac{-18}{7}=\dfrac{7}{12}-\dfrac{27}{7}.\dfrac{7}{-18}=\dfrac{7}{12}-\dfrac{-189}{126}=\dfrac{7}{12}+\dfrac{189}{126}=\dfrac{7}{12}+\dfrac{18}{12}=\dfrac{25}{12}\)

\(e,\left(\dfrac{7}{15}-\dfrac{11}{30}\right).\dfrac{-25}{3}=\left(\dfrac{14}{30}-\dfrac{11}{30}\right).\dfrac{-25}{3}=\dfrac{1}{10}.\dfrac{-25}{3}=\dfrac{-25}{30}=\dfrac{-5}{6}\)

\(f,\left(\dfrac{-5}{6}-\dfrac{1}{2}\right):\left(\dfrac{8}{15}-\dfrac{-3}{15}\right)=\left(\dfrac{-5}{6}-\dfrac{1}{2}\right):\left(\dfrac{8}{15}+\dfrac{3}{15}\right)=\left(\dfrac{-5}{6}-\dfrac{1}{2}\right):\dfrac{11}{15}=\left(\dfrac{-5}{6}-\dfrac{3}{6}\right):\dfrac{11}{15}=\dfrac{-4}{3}:\dfrac{11}{15}=\dfrac{-4}{3}.\dfrac{15}{11}=\dfrac{-60}{33}=\dfrac{-20}{11}\)

 

Answer 2

a: \(=\dfrac{15-12+2}{36}=\dfrac{5}{36}\)

b: \(=\dfrac{-2}{5}-\dfrac{12}{45}=\dfrac{-18-12}{45}=\dfrac{-30}{45}=\dfrac{-2}{3}\)

c: \(=\dfrac{2}{9}+\dfrac{5}{12}-\dfrac{3}{4}=\dfrac{8+15-27}{36}=\dfrac{-4}{36}=\dfrac{-1}{9}\)

d: \(=\dfrac{7}{12}-\dfrac{27}{7}\cdot\dfrac{7}{-18}=\dfrac{7}{12}+\dfrac{3}{2}=\dfrac{7+18}{12}=\dfrac{25}{12}\)

e: \(=\dfrac{14-11}{30}\cdot\dfrac{-25}{3}=\dfrac{3}{3}\cdot\dfrac{-25}{30}=\dfrac{-5}{6}\)

g: \(=\dfrac{-5-3}{6}:\dfrac{11}{15}=\dfrac{-8}{6}\cdot\dfrac{15}{11}=\dfrac{-120}{66}=\dfrac{-20}{11}\)

Answer 3

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