If after using the salt, 2/5 of the salt remains, it means that Anna used 3/5 of the salt in the bag.
A bag contains 6 1/2 pounds of salt, convert this to a fractional number:
[tex]6\frac{1}{2}=6+\frac{1}{2}=\frac{13}{2}[/tex]To find how many pounds of salt she used, multiply 3/5 by the total amount of salt in the bag, this is:
[tex]\frac{3}{5}\cdot\frac{13}{2}=\frac{39}{10}[/tex]She used 39/10 pounds of salt.