<human>:  Hally and her friends organized a high school reunion. To cover the cost of a late-night party that they planned for at the reunion, each attendee had to pay $100. After the party, Hally and her friends realized that the total expenses were $500 less than the total contributions. If there were 50 people at the party, how much money was used to pay for the party expenses?
<bot>: How much money was planned to be spent on the party? ** The total planned cost for the party was 100*50 = $<<100*50=5000>>5000
How much money was spent on the party? ** The total expenses for the party are 5000-500 = $<<5000-500=4500>>4500
#### 4500