2008 AIME I Problem 1

Of the students attending a school party, 60\% of the students are girls, and 40\% of the students like to dance. After these students are joined by 20 more boy students, all of whom like to dance, the party is now 58\% girls. How many students now at the party like to dance?

Leading zeroes must be inputted, so if your answer is 34, then input 034

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.