Step-by-step explanation:
Weight of moon rock on earth
[tex]= 20\frac{1}{2} \:lb\\\\
=\frac{20\times 2+1}{2} \:lb\\\\
= \frac {40+1}{2}\\\\
=\frac{41}{2}\:lb[/tex]
Weight of moon rock on moon
[tex]=\frac{41}{2}\:lb\:\times \frac{1}{6}\\\\
=\frac{41}{12}\:lb\\\\
=3\frac{5}{2}\:lb[/tex]
