\(\dfrac{7}{10}+\dfrac{-13}{5}=\dfrac{a}{20}\)
\(\Rightarrow\dfrac{14}{20}+\dfrac{-52}{20}=\dfrac{a}{20}\)
\(\Rightarrow\dfrac{-38}{20}=\dfrac{a}{20}\)
Vậy \(a=-38\)
\(\dfrac{7}{10}+\dfrac{-13}{5}=\dfrac{a}{20}\)
\(\Rightarrow\dfrac{14}{20}+\dfrac{-52}{20}=\dfrac{a}{20}\)
\(\Rightarrow\dfrac{-38}{20}=\dfrac{a}{20}\)
\(\Rightarrow a=-38\)
Vậy \(a=-38\)