There are 40 batteries in 10 packs. gavin wants to know how many batteries are in 1 pack. kylie wants to know how many batteries are in 5 packs.

We would first divide 40/10 to find how many batteries are in 1 pack so Gavin could know!

Using that number we would multiply by 5 so Kylie knows how many batteries are in 5 packs which is why we are multiplying by 5!

Let's begin:

40/10= 4

4 batteries in 1 pack 

Now we multiply this number 5 to find how many batteries are in 5 packs.

4x5= 20 batteries in 5 packs.

Our answer- 

Gavin: There are 4 batteries in 1 pack.
Kylie: There are 20 batteries in 5 packs.

(Doing this in steps. First we will find Gavin's answer, then in finding Gavin's answer we can find Kylie's answer.)
Step 1:
40 batteries in 10 packs.
Gavin wants to find out how many batteries in 1 pack.
Divide 40 by 10 to get 4
4 batteries are in 1 pack.

Step 2:
4 batteries per 1 pack.
Kylie wants to find out how many batteries in 5 packs. 
We do 4*5
4*5 = 20
20 batteries are in 5 packs.

Hope this helps you! (:
-Hamilton1757