Answer:
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {3}{7}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {3×3}{7×3}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {9}{2}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {1}{3}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {1×7}{3×7}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {7}{21}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac {9}{21}}\iff {\dfrac {7}{21}}[/tex]
[tex]{:}\leadsto [/tex][tex]\sf {\dfrac{9}{21}} \gt {\dfrac {7}{21}}[/tex]
[tex]\therefore[/tex][tex]\sf {\dfrac {3}{7}} \gt {\dfrac {7}{21}}[/tex]