You have the next equation:

Data: P=1.5
How much does that smoker spend on cigarettes:
Each day: As T is amunt of time in days, to find how much that smoker spend on cigarettes in one day you: Sustitute the T by 1 in the equation:
T=1day

Each day the smoker spends $12.375Each week: A week have 7 days
T=7days

Each week the smoker spends $86.625Each 30 day month:
T=30 days

Each 30 day month the smoker spends $371.25Each 365 day year:
T=365 days

Each 365 day year the smoker spends $4516.875