Devin wants to buy a new game system that costs $481.68 , including tax . He has already saved $225 for mowing lawns . Devin will walk the neighbor's dog 4 months to save the remaining amount of money needed to purchase the game system . He will earn the same amount of money each month . How much money must Devin earn each month to save the exact remaining amount needed ?
A. $256.68
B. $120.42
C. $56.25
D. $64.17