Mrs. Martins class will participate ina math-A-thon to raise money for a class trip. The math-A-thon workbook has 100 math problems. Students can raise money based on the number of math problems they answer correctly or by accepting a donation without regard to the number of math problems answered correctly. Prizes are rewarded to students who raise $50 or more. Daylyn, a student in the class, answers 80 math problems correctly. His grandmother pays $0.25 per correct answer. His uncle gives him a donation. If daylyn receives $45 total from his grandmother and uncle, how much money does his uncle give him? Write an equation and solve to find your answer.