Answer :
Lets take the number of granola bars being sold. If you sell 3 it's $1.50. You're trying to find how much it would be to sell 12 granola bars. If you multiply 3 by 4 you get 12, so multiply the cost ($1.50) by 4 to get $6.00. I hope this helps.
C.
3 granola bars=$1.50
12 granola bars total/3 per package=4 and $1.50*4 packages=$6.00