Hi guys!

I've been trying to figure out this math problem forever! I was hoping you could help out? =)

Month 1

- 100 sign-ups

Month 2

- 100 sign-ups

- 80 left from month 1

Month 3

- 100 sign-ups

- 80 left from month 2

- 40 left from month 1

Month 4

- 100 sign-ups

- 80 left from month 3

- 40 left from month 2

- 2 left from month 1

Average stay?

Thanks,

magnus