Sally receives a $7,000 gift from her grandmother before going to college. Before leaving she places a down payment on her classes on $500 and then spends $400 dollars a month while at school. Write a function that models the amount she has in the bank per month while she is at college where y is the money in her account and x is the number of months she attends college. A. y=500x+6500
B. y=-400x + 7000
C. y=400x+6500
D. y=-400x+6500