Answer :
[tex]\rm ^{20)}\frac{3}{8}= \frac{60}{160} \\ \\ ^{8)}\frac{7}{20}= \frac{56}{160} \\ \\ So~ \frac{3}{80}~is~bigger~because~60\ \textgreater \ 56. [/tex]
[tex] \frac{3}{8}= \frac{3}{8}* \frac{5}{5}= \frac{15}{40} \\ \frac{7}{20} = \frac{7}{20}* \frac{2}{2} =\frac{14}{40} \\ \\ \frac{3}{8}\ \textgreater \ \frac{7}{20} \\ \\ or \\ \\ 3*20\ \textgreater \ 7*8 \\ \\ \frac{3}{8}\ \textgreater \ \frac{7}{20} [/tex]