Answer:
Sally should charge $1,280 per month for 18 months.
Step-by-step explanation:
Sally has bought the land for $8,000 and she has invested in constructing the building $12,040. She has further invested $2,000 for future roof and common area expenses amount to $1,000. The total capital she has invested is $23,040. She should charge $1,280 per month for next 18 months in order to cover the bundled capital investment.