ABC Pty Ltd is a newly established small training organisation that provides private tuition focusing on Maths and English to high school students. Their billing cycle is 30 days in arrears (provide the lesson first then the parents will receive an invoice from ABC to pay a month later in full). It is predicted that 80% of parents will pay in full on time a month after the service and another 20% will be late paying in 2 months after the service. The cash balance at 01 January was $10,000. The followings are estimated revenue with respect to the first three months of the operations:

January: $20,000

February: $30,000

March: $50,000

Estimated expenses are

Wages 30% of revenue for the month

Stationary 5% of revenue for the month

Advertising: ABC only advertised the first month of service on google and social media, the remaining through word of mouth. Januarys adverting fee is $3,000 (ABC spent a lot of money in the first month advertising their business)

Monthly utilities: $2,000 (average)

What is the cash closing balance at the end of January? (no $, no space, no comma, use "-" for a negative amount)