On tuesday, 525 people bought tickets to the county fair. tickets cost $7 for adults and $3 for children. the total revenue from ticket sales on tuesday was $2775. the system of equations below represents the number of people and total sales for the county fair on tuesday, where x represents the number of child tickets and y represents the number of adult tickets. how many adult tickets were sold on tuesday? a.280 b.340 c.300 d.225