John has $900 in his bank account and plans to withdraw $75 per month. Write a linear equation for this situation and determine how many months it will take for his account to reach $0.
A. y = -75x+900 ; 12 months
B. y = 75x-900 ; 8 months
C. y = 75x+900 ; 12 months
D. y = 9x+75 ; 12 months