\(\dfrac{21}{35}+\dfrac{10}{35}=\dfrac{31}{35}\)
\(\dfrac{3}{5}+\dfrac{2}{7}=\dfrac{21}{35}+\dfrac{10}{35}=\dfrac{31}{35}\)
\(\dfrac{21+10}{35}=\dfrac{31}{35}\)
\(\dfrac{3}{5}\)+\(\dfrac{2}{7}\)=\(\dfrac{21}{35}\)+\(\dfrac{10}{35}\)=\(\dfrac{31}{35}\)