we know that

<u>Find the Greatest Common Factor (GCF)</u>
The GCF is equal to------> 
therefore
<u>the answer part a) is</u>
the greatest number of packs she can make is 
<u>Find the number of red pens in each pack</u>
Divide the total number of red pens by the total number of packs

<u>Find the number of blue pens in each pack</u>
Divide the total number of blue pens by the total number of packs

therefore
<u>the answer part b) is</u>
There are
in each pack
There are
in each pack