a,\(=\dfrac{9}{20}\)
b,\(=\dfrac{44}{35}\)
c,\(=\dfrac{155}{9}\)
d,\(=\dfrac{52}{35}\)
a)\(=\dfrac{10}{40}+\dfrac{8}{40}=\dfrac{18}{40}=\dfrac{9}{20}\)
b)\(=\dfrac{44}{35}\)
c)\(=\dfrac{5\times31}{9}=\dfrac{155}{9}\)
d)\(=\dfrac{2}{7}+\dfrac{6}{5}=\dfrac{10}{35}+\dfrac{42}{35}=\dfrac{52}{35}\)