8/5 + 3/7 = 56/35 + 15/35 = 71/35.
4/7 - 5/14 = 8/14 - 5/14 = 3/14.
\(1.\dfrac{48}{35}+\dfrac{15}{35}=\dfrac{63}{35}=\dfrac{21}{7}=3\)
\(2.\dfrac{8}{14}-\dfrac{5}{14}=\dfrac{3}{14}\)
\(\dfrac{8}{5}+\dfrac{3}{7}=\dfrac{56}{35}+\dfrac{15}{35}=\dfrac{71}{35}\)
\(\dfrac{4}{7}-\dfrac{5}{14}=\dfrac{8}{14}-\dfrac{5}{14}=\dfrac{3}{14}\)
Sorry,mình nhầm :
\(\dfrac{8}{5}+\dfrac{3}{7}=\dfrac{56}{35}+\dfrac{15}{35}=\dfrac{71}{35}\)
\(\dfrac{8}{5}+\dfrac{3}{7}=\dfrac{56}{35}+\dfrac{15}{35}=\dfrac{71}{35}\)
\(\dfrac{4}{7}-\dfrac{5}{14}=\dfrac{8}{14}-\dfrac{5}{14}=\dfrac{3}{14}\)