From 1 to 100

[Andre]

20

3 men walk into a hotel. They shared a room that cost $30,each men paid $10. However, after they had paid and gone to their room. The manager told the front desk todays special is $25 a room. The manager told the front desk lady to give them their $5 back. The front lady could not figure out how would she split $5 to three men. So she just gave them $1 each, since 3 times 1 is $3 and that means each paid $9 equally. So how much did the lady keep out of the $30?

Her whole tip for the stay.