Julio makes a mocktail every evening.  He uses 1 tablespoon of lime juice and tops with 1 cup of sparkling water.   He can usually squeeze 2 tablespoons of lime juice per lime.  After 30 days, if limes are 3 for $1.00, how much will he have spent on limes?
He uses 1 tablespoon of lime juice per drink so over 30 days that's 1*30 = 
<gadget id="calculator">1*30</gadget>
<output>30</output>
30 tablespoons of lime juice.
He can get 2 tablespoons of lime juice per lime and he will use 30 tablespoons of lime juice so he will need 30/2 = 15 limes.
The limes are 3 for $1.00 and he needs 15 limes so that's 15/3 = $5.00.

<result>5</result>