Can you break down the solution for me for this math problem: Katrina saw an ad that said if she signed up for her local recycling program, she could earn $5.00.  When she signed up, they told her for every friend that she referred, the friend would receive $5.00 and she would receive another $5.00 per friend.  That day, she had 5 friends sign up and another 7 friends by the end of the week.  How much money in total did she and her friends make?