A store sold two types of candy: chocolate bars for $1.50 each and lollipops for $2.25 each. On a particular day, the store sold $18.00 worth of these candies. If the number of chocolate bars sold was 1.5 times the number of lollipops sold, what was the total cost of the lollipops sold?
$4.50
$6.00
$9.00
$12.00
