At Al's Athletic Club, the monthly membership fee for a student is \ $ 25$ 2 5dollar sign 25 and the monthly membership fee for an adult is \ $ 40$ 4 0dollar sign 40. If Al's Athletic Club receives\ $ 12 {,} 250$ 1 2 , 2 5 0dollar sign, 12, comma, 250 in membership fees for the month of January, which of the following represents the relationship between the number of student memberships, xxx, and the number of adult memberships, yyy, at Al's Athletic Club for that month?