a: \(\dfrac{1}{4}+\dfrac{3}{8}=\dfrac{2}{8}+\dfrac{3}{8}=\dfrac{5}{8}\)
b: \(\dfrac{5}{12}+\dfrac{7}{3}=\dfrac{5}{12}+\dfrac{28}{12}=\dfrac{5+28}{12}=\dfrac{33}{12}=\dfrac{11}{4}\)
c: \(\dfrac{3}{16}+\dfrac{9}{4}=\dfrac{3}{16}+\dfrac{36}{16}=\dfrac{3+36}{16}=\dfrac{39}{16}\)
d: \(\dfrac{9}{14}-\dfrac{4}{7}=\dfrac{9}{14}-\dfrac{8}{14}=\dfrac{9-8}{14}=\dfrac{1}{14}\)
e: \(\dfrac{2}{5}-\dfrac{4}{15}=\dfrac{6}{15}-\dfrac{4}{15}=\dfrac{6-4}{15}=\dfrac{2}{15}\)
g: \(\dfrac{8}{7}-\dfrac{10}{21}=\dfrac{24}{21}-\dfrac{10}{21}=\dfrac{24-10}{21}=\dfrac{14}{21}=\dfrac{2}{3}\)