Fleonard bought 2 packs of batteries for x amount of dollars, how many packs of batteries could he purchase for $5.00 at the same rate

1.
The rate at which Leonard bought was 2 packs per x dollars, 

that is his buying rate was (2 packs)/(x dollars)=2/x (p/$)

2.

with 1 $ Leonard buys 2/x packs
then
with 5 $ Leonard buys (2/x)*5 = 10/x packs.

10/x packs

Draw a picture of 1/5 and get your answer from the picture