a/Ta có: \(\frac{7}{13}+\frac{6}{13}=1\) ;\(\frac{17}{23}+\frac{6}{23}=1\)
Vì \(\frac{6}{13}>\frac{6}{23}\)nên\(\frac{7}{13}< \frac{17}{23}\)
b/Ta có: \(\frac{12}{48}< \frac{12}{47}\) ; \(\frac{12}{47}< \frac{13}{47}\)\(\Rightarrow\frac{12}{48}< \frac{13}{47}\)