Brainteaser

See if you can solve this problem.

Each number shown below follows a certain rule. Figure out the rule and determine the missing number.

January	20
March	5
April	10
December	15
July	?

Is the answer?

1. 5
   
2. 10
   
3. 15
   
4. 20
   
5. 25
   

Check back in a couple of days. I will post the answer in a comment.