Human: Matt can buy key chains in packs of 10 for $20 or in packs of 4 for $12. How much money can he save if he chooses to buy 20 key chains at a lower price? Assistant:
The cost of each key chain in packs of 10 for $20 is $20/10=$2.
The cost of each key chain in packs of 4 for $12 is $12/4=$3.
There is a price difference of $3-$2=$1 per key chain between the two choices.
By buying 20 key chains at a lower price, Matt can save 20x$1=$20.