Maria started with $10. She has been saving $3 dollars each week to buy a softball bat. The amount of money Maria has depends on how many weeks she has been saving. Which expression represents Maria after x weeks?
A) f(x) = 10x + 3
B) f(x) = 3x + 10
C) f(x) = 10x - 3
D) f(x) = 3x - 10