Câu 1:
\(\dfrac{1313}{2121}=\dfrac{13}{21}>\dfrac{12}{21}\)
Câu 2:
\(a,\dfrac{-5}{4}+\dfrac{3}{4}=\dfrac{-2}{4}=\dfrac{-1}{2}\\
b,\dfrac{3}{13}:\dfrac{3}{-13}.\dfrac{1}{18}=\left(-1\right).\dfrac{1}{18}=\dfrac{-1}{18}\\
c,\dfrac{1}{3}+\dfrac{5}{8}-\dfrac{2}{3}+\dfrac{-5}{8}=\left(\dfrac{1}{3}-\dfrac{2}{3}\right)+\left(\dfrac{5}{8}+\dfrac{-5}{8}\right)=\dfrac{-1}{3}+0=\dfrac{-1}{3}\\
d,\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{11}-\dfrac{-5}{7}=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}+1\right)=\dfrac{-5}{7}.2=\dfrac{-10}{7}\)