An amphitheater charges $79 for each seat in Section A, $52 for each seat in Section B, and $30 for each lawn seat. There are three times as many seats in Section B as in Section A. The revenue from selling all 21,000 seats is $802,500. Let x be the number of seats in A, y be the number of seats in B, and z be the number of lawn seats. Which system of equations represents the situation?

Me with this assignment ! i only partially understand, so explain. also it's a work sample. at the championship bike race, steve and paula were fighting for first place. steve was 175 feet ahead of paula and had only 300 feet left to go. he was very tired and was going only 9 feet per second. paula was desperate to catch up and was going 15 feet per second. who won the bike race and by how far did she/he win?