Eric works at a food cart that sells hamburgers and hot dogs. Each hamburger costs $4.75 and each hot dog costs $3.75. On Monday afternoon, he sold a total of 84 hamburgers and hot dogs and collected a total of $339. Which system of equations could be used to find the number of hamburgers (x) Eric sold on Monday afternoon?
A. x + y = 84
3.75x + 4.75y = 339
B. x + y = 339
3.75x + 4.75y = 84
C. x + y = 84
3.75x + 4.75y = 339
D. x + y = 84
4.75x + 3.75y = 339