Final answer:
Lauren originally borrowed $9,000 from the bank, as indicated by substituting M=0 into the debt equation D=-200m+9000, resulting in D=9000.
Step-by-step explanation:
Lauren's debt after M months is represented by the equation D = -200m + 9000. To determine how much money Lauren borrowed, we need to find the value of D when M (months) is 0 since the loan amount would be the initial debt before any payments have been made. By plugging in M=0 into the equation, we get:
D = -200(0) + 9000
D = 9000
Therefore, Lauren originally borrowed $9,000.