a: =3/7-5/2-3/5
=30/70-175/70-42/70
=-187/70
b: \(=\dfrac{-4}{3}+\dfrac{-2}{5}+\dfrac{-3}{2}\)
\(=\dfrac{-40}{30}+\dfrac{-12}{30}+\dfrac{-45}{30}=\dfrac{-97}{30}\)
c: \(=\dfrac{4}{5}+\dfrac{2}{7}-\dfrac{7}{10}=\dfrac{56}{70}+\dfrac{20}{70}-\dfrac{49}{70}=\dfrac{27}{70}\)
\(a,\dfrac{3}{7}+\left(-\dfrac{5}{2}\right)+\left(-\dfrac{3}{5}\right)\)
\(=\dfrac{30}{70}+\dfrac{-175}{70}+\dfrac{-42}{70}=\dfrac{30+\left(-175\right)+\left(-42\right)}{70}=\dfrac{-187}{70}\)
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\(b,\left(-\dfrac{4}{3}\right)+\left(-\dfrac{2}{5}\right)+\left(-\dfrac{3}{2}\right)\)
\(=\dfrac{-40}{30}+\dfrac{-12}{30}+\dfrac{-45}{30}=\dfrac{\left(-40\right)+\left(-12\right)+\left(-45\right)}{30}=\dfrac{-97}{30}\)
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\(c,\dfrac{4}{5}-\left(-\dfrac{2}{7}\right)-\dfrac{7}{10}\)
\(=\dfrac{56}{70}-\dfrac{-20}{70}-\dfrac{49}{70}=\dfrac{56-\left(-20\right)-49}{70}=\dfrac{27}{70}\)
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\(d,\dfrac{2}{3}-\left[\left(-\dfrac{7}{4}\right)-\left(\dfrac{1}{2}+\dfrac{3}{8}\right)\right]\)
\(=\dfrac{2}{3}-\left[\left(-\dfrac{7}{4}\right)-\dfrac{7}{8}\right]\)
\(=\dfrac{2}{3}-\dfrac{-21}{8}\)
\(=\dfrac{16}{24}-\dfrac{-63}{24}=\dfrac{16-\left(-63\right)}{24}=\dfrac{79}{24}\)
